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The Senate Will Be Competitive Again In 2020, But Republicans Are Favored

Before the election, we took a way-too-early look at the 2020 battleground — in the U.S. Senate. We landed on this takeaway: Democrats really couldn’t afford to lose much ground in the 2018 elections or they’d dig themselves into a hole for 2020. Well, with the special-election runoff in Mississippi now over, we finally have a sense of how Democrats will be positioned in two years. In short, don’t be surprised if Republicans maintain control.

The Senate battleground is certainly better for Democrats in 2020 than it was this year, but it will still be an uphill climb. Republicans made a net gain of two seats this year, securing a 53-47 majority. This means Democrats must net four Senate seats in 2020 to recapture control — or three, if they also win the vice presidency. (The vice president casts the tiebreaking vote in the Senate.)

So what are the odds of that kind of gain? The election is still two years away, so we can’t really look at polling, but we can take a look at how Republican- or Democratic-leaning the states scheduled to hold a Senate election are to get a sense of which seats might be competitive.1 There will be at least 34 seats up for election in 2020,2 22 of which are currently held by Republicans and 12 of which are currently held by Democrats — a stark contrast to the 2018 cycle, when Democrats were on the hot seat. That said, to make the kind of gains they need, Democrats will have to overcome the partisan lean of some fairly red states, plus successfully defend two seats of their own in Republican territory.

The 2020 Senate battleground

Senators up for re-election in 2020 and their states’ partisan leans*

Name Party State Partisan Lean
Michael Enzi R Wyoming R+47.4
James Risch R Idaho R+34.9
James Inhofe R Oklahoma R+33.9
Mike Rounds R South Dakota R+30.6
Shelley Moore Capito R West Virginia R+30.5
Lamar Alexander R Tennessee R+28.1
Doug Jones D Alabama R+26.8
Tom Cotton R Arkansas R+24.4
Ben Sasse R Nebraska R+24.0
Pat Roberts R Kansas R+23.3
Mitch McConnell R Kentucky R+23.3
Steve Daines R Montana R+17.7
Bill Cassidy R Louisiana R+17.3
Lindsey Graham R South Carolina R+17.2
John Cornyn R Texas R+16.9
Cindy Hyde-Smith R Mississippi R+15.4
Dan Sullivan R Alaska R+14.9
David Perdue R Georgia R+11.8
OPEN (Jon Kyl)† R Arizona R+9.3
Joni Ernst R Iowa R+5.8
Thom Tillis R North Carolina R+5.1
Jeanne Shaheen D New Hampshire R+1.7
Mark Warner D Virginia D+0.1
Gary Peters D Michigan D+1.3
Cory Gardner R Colorado D+1.5
Tina Smith D Minnesota D+2.1
Susan Collins R Maine D+4.9
Tom Udall D New Mexico D+7.2
Jeff Merkley D Oregon D+8.7
Dick Durbin D Illinois D+13.0
Cory Booker D New Jersey D+13.3
Chris Coons D Delaware D+13.6
Jack Reed D Rhode Island D+25.7
Ed Markey D Massachusetts D+29.4

* Partisan lean is the average difference between how a state or district voted and how the country voted overall, where 2016 presidential election results are weighted 50 percent, 2012 presidential election results are weighted 25 percent, and results from elections for the state legislature are weighted 25 percent.

† Sen. Jon Kyl was appointed to serve out the remainder of the late John McCain’s term but has declared he will not run for a full term in 2020.

Sources: U.S. Senate, The New York Times

The two Republican senators who represent blue states — Susan Collins of Maine and Cory Gardner of Colorado — are probably Democrats’ two most obvious 2020 targets. But despite the partisan leans of their states, they may prove formidable opponents. As chairman of the National Republican Senatorial Committee, the arm of the party tasked with electing Senate Republicans, Gardner will doubtlessly have access to a ton of campaign cash, although he probably wishes his approval ratings were higher than 39 percent approve, 37 percent disapprove. Collins looks like she’s in a stronger position, with an approval rating of 53 percent (compared to 38 percent disapproving) in her blue-tinted home state. However, her reputation as an independent voice in the GOP caucus may have taken a hit when she voted to confirm Brett Kavanaugh to the Supreme Court. A late-October Emerson poll found that 47 percent of likely 2018 voters were less likely to vote for Collins as a result of her Kavanaugh vote,3 and a crowdsourced campaign has already harnessed liberals’ anger to raise $3.7 million for her hypothetical Democratic opponent. However, it’s anyone’s guess whether the Kavanaugh vote will still resonate two years from now.

So let’s say the Democrats do capture Maine and Colorado. They still have to defeat two Republicans in red states to reach 51 seats. At first glance, the least daunting targets appear to be Thom Tillis of North Carolina and Joni Ernst of Iowa. Iowa is slightly redder than North Carolina, but Iowa is also one of the more elastic states in the U.S., meaning it responds more to shifts in the national mood. Let’s assume for the moment that each state will vote exactly in line with its partisan lean — that is, whatever its partisan lean metric is plus or minus the national popular vote (so, for example, a state that normally leans D+2 would vote to elect a Republican candidate by 2 points when the country at large was leaning R+4).4 If that were the case, a political environment of D+6 in 2020 would be enough to defeat both Tillis and Ernst. (For reference, the political environment leaned Democratic by more than 8 points this year, so if President Trump continues to be unpopular, this isn’t that unrealistic.) But Tillis and Ernst will probably retain some degree of incumbency advantage, even if it is diminished relative to past years. Incumbency was worth about 6 percentage points in 2018, so if that stays the same, it might take something like a D+12 national environment to topple Tillis and oust Ernst. Then again, neither is especially popular, and the quality of their opponents will also play a role. For example, if former Gov. Tom Vilsack is the Democratic candidate in Iowa, he too would enjoy the benefits of already having held a statewide office, such as name recognition and access to funds.

Still, Arizona might prove an easier Democratic target. The Grand Canyon State is 9 points more Republican-leaning than the nation as a whole (and 4 points more Republican-leaning than Iowa or North Carolina), but it will almost certainly be an open seat. (Current GOP Sen. Jon Kyl, who was appointed to the seat vacated by the late Sen. John McCain, has said he will not run in 2020.) Just this month, Democrats won an open U.S. Senate seat in Arizona by about 2 points. In 2020, Republicans might even run the same candidate they ran in 2018.

Finally, Democrats will have to successfully defend all of their current seats, including two in red states. One of the pair shouldn’t be too hard, assuming Sen. Jeanne Shaheen of New Hampshire runs for a third term; the Granite State is only slightly Republican-leaning, and Shaheen is pretty popular. But the other seat belongs to Sen. Doug Jones in dark-red Alabama. Defending Jones might be Democrats’ most difficult task of all, given that 2018 was an object lesson in how state partisanship can overwhelm the incumbency advantage in the Senate (just ask Claire McCaskill, Joe Donnelly and Heidi Heitkamp). Although Jones enjoys relative popularity (43 percent of Alabamians approve of his performance, while 30 percent disapprove), he is unlikely to face another opponent as flawed as Roy Moore was.5 And Alabama has a partisan lean of R+27, so it would take a heck of a blue wave — or a heck of an incumbency advantage — to save him.

My educated guess this far out is that Democrats’ best path to a Senate majority in 2020 lies in winning Maine, Colorado and Arizona, plus the vice presidency. In this scenario, either Jones would have to win or Democrats would also have to flip either Iowa or North Carolina. In a political environment where Trump remains unpopular and the Democratic presidential nominee wins by enough to have coattails, that’s not too hard to imagine. But barring a clear blue tinge to 2020, Republicans remain favored in the Senate for the foreseeable future.


  1. According to FiveThirtyEight’s partisan lean metric, which is the average difference between how a state or district votes and how the country votes overall, where 2016 presidential election results are weighted 50 percent, 2012 presidential election results are weighted 25 percent and results from elections for the state legislature are weighted 25 percent. Note that partisan leans may shift a bit, but probably not a lot, once 2018 results are incorporated.

  2. Thirty-three seats are up for election on their regular schedule, and there will be at least one special election, which will be to fill John McCain’s old seat. Other special elections may be added in the next two years.

  3. Just 37 percent said it made them more likely to vote for her, and 16 percent said it didn’t make a difference. Change Research came out with a similar finding.

  4. It’s not as ridiculous as it sounds.

  5. Then again

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