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Kyrsten Sinema Is Confounding Her Own Party. But … Why?

Most Democrats in Congress are united around the Democratic agenda, but a small number of senators and representatives have so far been able to hold up its passage. “I need 50 votes in the Senate. I have 48,” President Biden said last week, regarding his social spending bill. As for who is standing in the way, his blame was clear: “Two. Two people.”

Those two people are Sens. Joe Manchin and Kyrsten Sinema. The two moderates have forced Democrats to water down several priorities (such as election reform and the $3.5 trillion budget bill) and are blocking more ambitious reforms entirely (such as abolishing the filibuster). But while congressional observers — from the commander-in-chief on down — usually mention Manchin and Sinema in the same sentence, it’s a mistake to lump together their resistance to their party’s priorities. Manchin’s centrism is unsurprising: He has been a conservative Democrat his entire career, and his home state of West Virginia is so red that it might be politically impossible for him to move left, even if he wanted to. 

But neither is true of Sinema. Once a staunch progressive, Arizona’s senior senator has taken a hard turn to the right. On the surface, that appears to have been an effort to make her more electable by courting moderate and conservative voters. If so, she may have overcompensated: Arizona is no West Virginia, and no other swing-state senator has vexed Democratic leadership so thoroughly. In fact, Sinema’s established such a firm anti-progressive reputation that she may have lost the support of enough Democrats to endanger her reelection just the same. 

Sinema’s resistance to core pieces of her party’s agenda may seem puzzling from an electoral perspective, and it’s possible that a motivation other than winning reelection is behind her contrarianism (more on that later). But it’s also possible that she’s striking the ideal strategic balance between primary and general election electability.

So, is Sinema right?

Are Democrats really that far from passing Biden’s agenda?

Sinema began her political career as a self-described “Prada socialist.” Originally a member of the Arizona Green Party, she was a vocal liberal activist who organized anti-war protests and marches for immigrants’ rights. After a failed bid for the Arizona state legislature in 2002, she switched to the Democratic Party and went on to serve three terms in the state House and one in the state Senate. According to ideology scores for state legislators calculated by political scientists Boris Shor and Nolan McCarty, she was the House’s second- or third-most liberal member during her tenure, and the Senate’s single most liberal member in 2011-12.

But when she was elected to the U.S. Congress in 2012, a switch flipped. She immediately became the most conservative Democrat in the House of Representatives, according to DW-Nominate, which uses voting records to quantify the ideology of every member of Congress on a scale from 1 (most conservative) to -1 (most liberal). She has a career DW-Nominate score of -0.103, which currently makes her the second-most conservative Democrat in the Senate, after Manchin.

The conventional wisdom is that Sinema rushed toward the center for electoral reasons, as she moved from representing a solidly blue electorate to purpler ones. Former President Obama carried her state legislative seat by 26 percentage points in 2008 (according to local analyst Aseem Chandi), but Obama carried her congressional seat by less than 5 points in 2012. While her district became more safely Democratic later in her House career, she may have already been laying the groundwork for her Senate run. “Kyrsten has always had her eyes on a larger electorate,” Tempe City Councilwoman Lauren Kuby told The New York Times in 2018. (Tempe is a city in Sinema’s old district.) And to win a statewide campaign, Sinema needed to win over even more swing voters: Former President Trump carried Arizona by almost 4 points in 2016. 

Sens. Kyrsten Sinema and Joe Manchin in an elevator, with the doors closing in front of them.

related: Are Democrats Dysfunctional Or Just Disagreeing?

But while no one denies that Arizona is a tough state for Democrats to win, it’s not nearly as tough as Manchin’s West Virginia, which Trump carried by a whopping 42 points in 2016. West Virginia is no swing state; it’s one of the reddest states in the entire country. And while six non-Sinema Democrats have won a statewide election in Arizona since 2018 — including Biden in 20201 — Manchin is the only Democratic statewide elected official left in West Virginia.

In other words, Democrats are lucky that Manchin is in the Senate at all. Because of how red West Virginia is, a typical senator from the state would almost certainly be a Republican.2 Indeed, based on Trump’s margin in West Virginia in 2016, we’d expect that a generic replacement for Manchin would have voted in line with Trump’s position 89.3 percent of the time during his presidency. Manchin, though, voted with Trump just 50.4 percent of the time — a lot for a Democrat, but not a lot considering the partisanship of his home state.

Using the same methodology, we’d have expected a generic replacement for Sinema to vote with Trump just 39.8 percent of the time — a reflection of the purpler partisanship of her state and her congressional district at the time. Yet Sinema voted with him 50.4 percent of the time too, as much as Manchin. That made her the only Democratic senator who voted with Trump significantly3 more often than expected based on the politics of senators’ states. Her voting record during the Trump years looked more like Manchin’s, Sen. Joe Donnelly’s, Sen. Heidi Heitkamp’s or Sen. Claire McCaskill’s — all Democrats from substantially redder states.

Sinema voted with Trump more often than expected

How often Democratic senators voted in line with former President Trump during his administration, compared with how often we’d expect them to do so based on Trump’s 2016 margin in their home state

Senator State 2016 Margin Trump Score Predicted Score Diff.
Heitkamp ND R+36 54.8% 91.5% -36.8%
Donnelly IN R+19 54.2 83.3 -29.1
Manchin WV R+42 50.4 89.3 -38.9
Sinema AZ R+4 50.4 39.8 +10.6
McCaskill MO R+19 45.8 83.0 -37.2
Nelson FL R+1 43.4 56.8 -13.4
King ME D+3 37.2 44.1 -6.9
Jones AL R+28 35.3 84.5 -49.2
Warner VA D+5 34.9 40.1 -5.2
Rosen NV D+2 34.6 60.4 -25.9
Tester MT R+20 30.2 80.5 -50.3
Shaheen NH EVEN 29.7 48.9 -19.2
Carper DE D+11 29.5 31.8 -2.3
Kaine VA D+5 29.5 40.1 -10.7
Coons DE D+11 28.9 31.9 -3.0
Casey PA R+1 28.7 50.8 -22.1
Hassan NH EVEN 28.7 48.8 -20.1
Peters MI EVEN 28.1 49.8 -21.7
Cortez Masto NV D+2 27.9 45.1 -17.1
Stabenow MI EVEN 27.9 49.9 -22.0
Bennet CO D+5 27.3 41.7 -14.4
Klobuchar MN D+2 26.7 47.2 -20.5
Heinrich NM D+8 26.6 35.8 -9.2
Brown OH R+8 25.8 64.2 -38.4
Murphy CT D+14 25.2 29.6 -4.4
Udall NM D+8 25.2 36.3 -11.1
Cardin MD D+26 25.0 20.9 +4.1
Duckworth IL D+17 25.0 26.7 -1.7
Smith MN D+2 25.0 43.3 -18.3
Cantwell WA D+15 24.2 27.6 -3.4
Feinstein CA D+30 24.2 20.1 +4.2
Durbin IL D+17 23.8 26.3 -2.5
Franken MN D+2 23.6 49.5 -25.9
Murray WA D+15 23.6 28.1 -4.5
Leahy VT D+26 23.4 20.7 +2.7
Schatz HI D+32 23.4 19.4 +4.1
Reed RI D+16 23.3 27.8 -4.5
Schumer NY D+22 23.3 23.1 +0.1
Whitehouse RI D+16 22.8 27.7 -4.9
Baldwin WI R+1 22.7 51.0 -28.3
Van Hollen MD D+26 22.7 21.5 +1.2
Hirono HI D+32 22.5 19.2 +3.2
Menendez NJ D+14 22.0 28.0 -5.9
Blumenthal CT D+14 20.3 29.4 -9.1
Kelly AZ R+4 20.0 26.2 -6.2
Wyden OR D+11 18.6 32.3 -13.7
Markey MA D+27 16.5 21.3 -4.8
Harris CA D+30 16.4 20.9 -4.5
Sanders VT D+26 16.1 22.1 -6.0
Booker NJ D+14 16.0 29.0 -13.1
Warren MA D+27 15.5 21.6 -6.0
Merkley OR D+11 15.5 32.3 -16.8
Gillibrand NY D+22 12.4 24.2 -11.8
Luján NM D+8 12.4 24.3 -12.0
Hickenlooper CO D+5 0.0 3.0 -3.0

Sources: ProPublica; Daily Kos; Cook Political Report; U.S. Senate; @unitedstates

In the current congress, Sinema has voted perfectly in line with the Biden administration and her party on bills that came up for a vote. But as we’ve seen with negotiations over the reconciliation bill and more, that leaves a lot out. Sinema still ranks as more ideologically conservative than other Democratic senators from once-red-but-trending-blue states: Jon Ossoff (who has a DW-Nominate score of -0.448 so far) and Raphael Warnock (-0.380) of Georgia, and even her fellow Arizonan, Mark Kelly (-0.186).

If Sinema is acting moderate for electoral reasons, she clearly disagrees with the conventional wisdom about how moderate a swing-state senator needs to be. On one hand, maybe she has a point: Donnelly, Heitkamp and McCaskill all lost reelection in 2018, as did Sen. Bill Nelson, whose home state of Florida is about as purple as Arizona but who voted with Trump less often than Sinema did. All four voted with Trump significantly less often than we’d have expected given the partisanship of their state, suggesting that Sinema’s strategy of hewing closer to expectations might have been smarter. (Although this doesn’t justify her approach of voting with Trump more often than expected.) On the other hand, political science research has found that candidates and congressional aides are really bad at assessing where voters stand on the issues. One 2013 study found that politicians overestimated by several percentage points how conservative their constituents were, in direct contradiction of Sinema’s entire theory of the case.

Maybe Sinema just figures she can’t be too careful. But if that’s the case, she’ll just win reelection in a landslide, right? Perhaps — but there are also downsides to moving too far to the center. For every inch of ground she gains with swing voters by demonstrating her independence from the Democratic Party, she risks alienating the Democratic base. And it’s not at all clear whether that’s a winning electoral tradeoff.

In a convenient natural experiment, an OH Predictive Insights poll from early September asked Arizona registered voters their opinions of Sinema and Kelly, who serves as a kind of control variable for Sinema: a Democratic senator from Arizona who isn’t a thorn in his party’s side. Accounting for the poll’s margin of error, the two had virtually identical favorable and unfavorable ratings: 46 percent to 39 percent for Sinema, 47 percent to 43 percent for Kelly. 

But that topline similarity obscured major differences in their underlying coalitions. Kelly had very conventional party splits in his popularity: Democrats viewed him favorably, 80 percent to 11 percent, while Republicans viewed him unfavorably, 73 percent to 20 percent. Sinema’s heterodoxy, though, earned her a much more lukewarm rating among Democrats: 56 percent favorable, 30 percent unfavorable. At the same time, it endeared her to Republicans, an impressive 40 percent of whom had a favorable opinion of her (versus 48 percent who had an unfavorable opinion). Independents, though, rated the two of them virtually the same.

Sinema is presumably betting that Democrats who dislike her will vote for her regardless, and that at least some Republicans who like her will vote for her, too. It’s not an outlandish notion: Those liberal Democrats, as frustrated as they are at Sinema, will probably find her Republican opponent more odious, and while there aren’t a lot of voters who can be persuaded to cross party lines, they do exist. But it’s just as possible that some of those Democratic disapprovers will be so frustrated with Sinema that they’ll skip voting in the Senate race. And just because a Republican voter likes Sinema doesn’t mean they’ll choose her over a candidate of their own party. Since Sinema is next up for reelection in 2024, she’ll be asking those voters to cast ballots for her at the same time as they are very likely voting for the Republican presidential candidate. That’s a big ask considering how few voters split their tickets in this highly polarized era. 

If Democratic opinion of Sinema sinks low enough, she could even be in danger of losing in a primary. Progressives are already gearing up to challenge her; two groups have formed to help fund her eventual opponents, and another is hoping to recruit progressive Rep. Ruben Gallego to run against her. 

It’s extremely rare for elected incumbent senators to lose their primaries. Only five have done so this century: Republican Sen. Bob Smith in 2002, Democratic Sen. Joe Lieberman in 2006, Democratic Sen. Arlen Specter in 2010, Republican Sen. Lisa Murkowski in 20104 and Republican Sen. Richard Lugar in 2012.5 But it’s also rare for incumbent senators to poll as poorly among their own party’s voters as Sinema does. In addition to the OH Predictive Insights poll, Democratic registered voters in Arizona gave her a 46 percent favorable rating and a 40 percent unfavorable rating in a Morning Consult survey conducted across July, August and September. And Democratic pollster Civiqs recently found her severely underwater among the same population: 17 percent favorable to 65 percent unfavorable.

On average, Sinema currently has a 40 percent favorable rating and a 45 percent unfavorable rating among Democratic registered voters. Those are worse favorability ratings than Lugar, Specter, Lieberman and Smith had among voters of their respective parties in the closest polls we could find to their primaries. (We couldn’t find a poll that measured Murkowski’s favorability among Republicans before her 2010 primary, but a post-election Public Policy Polling survey did peg her at 48 percent approval to 46 percent disapproval among Republicans.)

Sinema is less popular than senators who lost primaries

Favorability of elected incumbent senators who lost primaries since 2000 among voters in their own party, compared with Kyrsten Sinema’s average favorable and unfavorable ratings among Democrats in three 2021 polls

Senator State Party Favorable Unfavorable Net
Arlen Specter PA D 50% 33% +17
Bob Smith NH R 45 30 +15
Joe Lieberman CT D 40 29 +11
Richard Lugar IN R 43 43 0
Kyrsten Sinema AZ D 40 45 -5

Ratings are from the most recent poll before each primary. Lisa Murkowski lost in a Republican primary in 2010 but is not listed here because we could find no preelection poll of her favorability ratings among Alaska Republicans.

Sources: Greg Giroux, Quinnipiac, University of New Hampshire, Howey/DePauw, OH Predictive Insights, Morning Consult, Civiqs

Of course, Sinema’s primary is still almost three years away, so there is plenty of time for her numbers to improve — if she lets them. But if nothing changes, she could be vulnerable. And even if she prevails, a tough primary could make it harder to win the general election by sapping her resources and creating Democratic disunity. Arizona’s primary is relatively late on the calendar (August), which may not give primary winners enough time to recover and run a strong general election campaign. (Then-Rep. Martha McSally’s campaign partly blamed her tough Republican primary for her loss to Sinema in the 2018 general election.)

I do buy that Democrats should be worried about Virginia gubernatorial race: Silver

What’s the right balance for Sinema — or any senator, really — to strike between concern for the primary and concern for the general? It may depend on the partisanship of their state. The table below lists all the elected incumbent senators who have lost reelection since 2000 in either a primary or general election. Perhaps unsurprisingly, all the incumbents who lost primaries represented states that leaned toward their party (though some, like Specter and Smith, did represent swing states). All the incumbents who lost reelection on the opposite party’s home turf did so in the general.

Senators who lost primaries weren’t in unsafe seats

Elected incumbent senators who have lost either primaries or general elections since 2000, plus Kyrsten Sinema, and the FiveThirtyEight partisan lean* of their state at the time

Incumbent Party Year State Lost? Partisan Lean
Lisa Murkowski R 2010 AK Primary +24
Ted Stevens R 2008 AK General +24
Conrad Burns R 2006 MT General +17
Joe Lieberman D 2006 CT Primary +13
David Perdue R 2020 GA General +12
Richard Lugar R 2012 IN Primary +11
Elizabeth Dole R 2008 NC General +10
George Allen R 2006 VA General +10
Bob Smith R 2002 NH Primary +5
Jim Talent R 2006 MO General +4
Russ Feingold D 2010 WI General +4
Mike DeWine R 2006 OH General +2
Arlen Specter D 2010 PA Primary +2
John Sununu R 2008 NH General +1
Dean Heller R 2018 NV General +1
Mark Udall D 2014 CO General +1
William Roth R 2000 DE General 0
John Ashcroft R 2000 MO General 0
Kelly Ayotte R 2016 NH General 0
Slade Gorton R 2000 WA General -2
Spencer Abraham R 2000 MI General -2
Cory Gardner R 2020 CO General -2
Rick Santorum R 2006 PA General -2
Norm Coleman R 2008 MN General -4
Gordon Smith R 2008 OR General -4
Rod Grams R 2000 MN General -4
Bill Nelson D 2018 FL General -5
Kay Hagan D 2014 NC General -6
Blanche Lincoln D 2010 AR General -7
Kyrsten Sinema D 2024 AZ ? -8†
Tim Hutchinson R 2002 AR General -9
Max Cleland D 2002 GA General -10
Chuck Robb D 2000 VA General -10
Mark Kirk R 2016 IL General -13
Mark Pryor D 2014 AR General -17
Mary Landrieu D 2014 LA General -18
Joe Donnelly D 2018 IN General -18
Claire McCaskill D 2018 MO General -19
Mark Begich D 2014 AK General -20
Tom Daschle D 2004 SD General -21
Doug Jones D 2020 AL General -28
Scott Brown R 2012 MA General -28
Lincoln Chafee R 2006 RI General -29
Heidi Heitkamp D 2018 ND General -31

*Partisan lean is the average margin difference between how a state or district votes and how the country votes overall. This version of partisan lean, meant to be used for congressional and gubernatorial elections, is calculated as 50 percent the state or district’s lean relative to the nation in the most recent presidential election, 25 percent its relative lean in the second-most-recent presidential election and 25 percent a custom state-legislative lean. In this case, positive numbers are toward the senator’s party.

†Arizona’s partisan lean for 2024 is not yet available; this is the lean for 2022.

Sources: Greg Giroux, election results

While Arizona is a swing state, it is still slightly Republican-leaning. (Biden carried it by only a hair in 2020, suggesting that he would have lost there if the national environment hadn’t been so Democratic-leaning.) So perhaps Sinema is right not to fear a primary challenge; it would be unprecedented in recent history for someone in her position to lose renomination. Then again, few politicians have pushed the envelope of what their base will tolerate as much as Sinema has. It’s an obvious point, but while Arizona might be light red overall, the Democratic primary electorate will be mostly Democrats and Democratic leaners — a group that, in Arizona, self-identifies as 61 percent liberal and only 33 percent moderate

The reason that Democratic senators in red states and Republican senators in blue states tend not to lose their primaries isn’t because members of the opposite party are voting for them in the primary; it’s more that voters are afraid to throw them out, or that opponents are afraid to challenge them, lest it endanger the party’s hold on the seat in the general election. But Sinema is putting to the test whether this concern outweighs the grassroots dissent against her. That’s a big risk.

Up to now, we haven’t questioned the assumption that Sinema’s maverickness is motivated by a desire to win elections. But as we’ve seen, if that’s Sinema’s goal, her strategy for attaining it is unconventional at best and counterproductive at worst. That naturally raises one final question: If not winning reelection, what else could be motivating Sinema?

It may be her donors. In a September report, liberal group Accountable.US found that Sinema raised at least $923,065 from business interests that opposed Biden’s budget reconciliation plan, such as the U.S. Chamber of Commerce, a longtime Sinema ally. She’s also been the recipient of large donations from the pharmaceutical industry, which critics have blamed for her opposition to letting Medicare negotiate down drug costs. Of course, it’s possible that the causation is reversed — that such interest groups are donating to her because they like her positions on these issues. That said, a recent study found that politicians did adjust their positions based on donor preferences. “When the national donor base prefers a different outcome than a representative’s general and primary electorates,” the authors wrote, “overwhelmingly the member chooses the donor-favored position.”

Another explanation for Sinema’s centrism could be that she genuinely believes in it. In her 2009 book “Unite and Conquer,” Sinema described how she was initially frustrated at her inability to get things done in the state legislature — so she decided to stop being a “bomb-thrower” and start working with Republicans. Perhaps now, after so many years of embedding with the GOP to get things done (this is the first time she has ever served in a legislative chamber controlled by Democrats), she has internalized the conservatism of her peers — and even embraced bipartisanship as a policy goal unto itself. (That would explain her fierce opposition to ending the filibuster and her dogged negotiation of a bipartisan $1 trillion infrastructure bill earlier this year.) What else, besides personal conviction, can explain why she has maintained her contrarianism in the face of frustrated colleagues, aggressive protesters and the potential end of her political career? It could be that she really is acting on principle. Or it could be that she thinks this is her smartest move politically. Or it could be some combination of both. Unfortunately, we might never know for sure.

CORRECTION (Oct. 11, 2021, 5:00 p.m.): An earlier version of the second table in this article misspelled Sen. Kyrsten Sinema’s first name.

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  1. The other five are Sen. Mark Kelly, Secretary of State Katie Hobbs, Superintendent of Public Instruction Kathy Hoffman and Corporation Commissioners Sandra Kennedy and Anna Tovar.

  2. And if so, that would hand Republicans control of the Senate, considering Democrats have the majority now only by dint of Vice President Kamala Harris’s tie-breaking vote.

  3. More than 5 percentage points more often.

  4. Lieberman and Murkowski, however, went on to win their general elections as independents.

  5. In addition, appointed Sen. Luther Strange lost the Alabama Republican primary in 2017, and Sen. Bob Bennett lost renomination at the Utah Republican convention in 2010.

Nathaniel Rakich is a senior editor and senior elections analyst at FiveThirtyEight.