What Are The Most Vulnerable Senate Seats In 2024?
Welcome to FiveThirtyEight’s politics chat. The transcript below has been lightly edited.
nrakich (Nathaniel Rakich, senior elections analyst): Things are heating up in 2024’s U.S. Senate races! On Monday, Democratic Rep. Elissa Slotkin announced her candidacy for Michigan’s open Senate seat, and last week, Democratic Sen. Jon Tester declared he was running for reelection in Montana. (All these early announcements are putting the 2024 presidential race to shame. C’mon, Joe Biden and Ron DeSantis, step on it!)
So for this week’s FiveThirtyEight politics chat, Alex Samuels and Geoffrey Skelley are joining me to check in on how the battle for the Senate is shaping up. How’s it going, guys?
alex (Alex Samuels, politics reporter): Howdy, Nathaniel! 🤠 All is well over here. And given my pro-chat proclivities, I’m very glad we’re doing these regularly now!!
nrakich: OK, so first things first — Slotkin and Tester running is good news for Democrats, right?
geoffrey.skelley (Geoffrey Skelley, senior elections analyst): In the grand scheme of things, Tester’s decision is one of the most important of the cycle. If he hadn’t sought reelection, Democrats would have been cooked in Montana.
Tester’s ability to outrun Montana’s red partisan lean is a critical part of this. Former President Donald Trump carried Montana by 16 percentage points in 2020, placing the state roughly 21 points to the right of the country as a whole. In that same election, a relatively popular Democratic governor (Steve Bullock) still lost 55 percent to 45 percent against GOP Sen. Steve Daines. But Tester has survived a presidential cycle before, defeating a strong opponent (Republican Rep. Denny Rehberg) in 2012, even while Mitt Romney was carrying the state by 14 points. The state may be a tad redder now than it was back then, but Tester makes this election a toss-up instead of probably a “Solid Republican” race.
alex: That’s right, Geoffrey. One more reason it’s good for Democrats that Tester is running: Senate incumbents rarely lose. One of the worst recent cycles for them was 1980, when Ronald Reagan’s coattails helped Republicans pick up 12 seats. But since then, according to Open Secrets, the reelection rate for Senate incumbents has never dropped below 75 percent. In fact, it’s more common for incumbents to win 85 percent or more of races. Remember last year, too, when Republicans were excited at the prospect of picking up multiple seats and not a single incumbent lost.
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geoffrey.skelley: As for Slotkin, she seems like a solid candidate for Democrats. Having worked for the CIA and Defense Department before entering congressional politics, she’s got a background in national security that might appeal to more centrist voters. She’s also a very strong fundraiser. To that point, her Senate campaign brought in $1.2 million on its first day.
She won’t necessarily make people on the left happy, but Michigan is a purplish state and Slotkin has won on purple turf three times now in varied environments: In 2018, she beat an incumbent in a very Democratic-leaning cycle; in 2020, she held onto her seat in a more neutral presidential year; and in 2022, she won reelection by a larger margin than ever before, even though that was a more favorable year for the GOP nationwide.
nrakich: Yeah, our friends at Split Ticket have calculated a WAR score (after the baseball stat wins above replacement) for politicians to quantify candidate quality, and Slotkin has consistently been a strong performer.
She’ll need to get past the primary first, though. As you mentioned, Slotkin isn’t a favorite of the party’s left flank. For example, she voted to nullify a Washington, D.C., law to reduce the maximum penalties for certain crimes. But so far, she’s managed to clear the field. Other potentially strong candidates, like Lt. Gov. Garlin Gilchrist and Rep. Haley Stevens, have given the race a pass.
geoffrey.skelley: The other major politician who might run is Secretary of State Jocelyn Benson, who would probably have a solid campaign slogan as a candidate who’s “protected democracy” in Michigan. But one outside name of interest is Nasser Beydoun, a businessman who has held leadership roles in a number of organizations focused on the Arab American community in Michigan, which has a larger share of people who claim Arab ancestry than any other state (around 2 percent).
alex: What might benefit Slotkin — or any other Democrat, really — is the fact that Michigan is a state where there’s not a particularly strong GOP challenger waiting in the wings, either. Newly elected Rep. John James, who has lost two successive Senate races, said he won’t run for the seat. And I know there’s chatter about former Rep. Peter Meijer, but his vote to impeach Trump after the Jan. 6 insurrection could make it more challenging for him to win a GOP primary.
nrakich: Yeah, how are the candidate pools shaping up on the Republican side? Not just in these two states, but everywhere?
geoffrey.skelley: So far, the Michigan GOP has only one declared candidate of note — State Board of Education member Nikki Snyder — but she failed to make the ballot to run against Slotkin back in 2020. A number of other candidates have expressed interest in running, but it’s unclear at this point who else might jump in.
In Montana, though, there are a couple of high-profile Republicans who might run: the state’s two House members, Matt Rosendale and Ryan Zinke. Rosendale, however, lost to Tester in 2018, and Zinke has a number of scandals from his days serving as Trump’s secretary of the interior, which may help explain his underwhelming 3-point win in 2022 to return to the House in a seat that’s about 10 points redder than the nation as a whole. The GOP may be better off with a candidate like state Attorney General Austin Knudsen, who might also get in.
alex: It’s telling that the National Republican Senatorial Committee — which largely stayed neutral last year — has signaled an interest in being more involved in open-seat primaries this go-around. Then again, maybe that strategy isn’t that surprising considering some of the party’s most controversial losers from 2022 are launching campaigns or considering running in 2024.
nrakich: Yeah, we tracked NRSC endorsements during the 2022 cycle, and it didn’t endorse a single nonincumbent Senate candidate — a deliberate strategy by then-NRSC Chair Rick Scott that may have backfired given how weak Republican Senate candidates were that year. But this year, it has already essentially endorsed Rep. Jim Banks in Indiana, for instance, and more endorsements could be coming down the pike.
alex: Separately, Senate Minority Leader Mitch McConnell would probably advocate for their involvement, no? He was arguably the most vocal Republican decrying the party’s candidate quality last year.
geoffrey.skelley: I think the jury is still out on just how much the NRSC will involve itself in the 2024 primaries. In a state like Montana, if there are a couple major officeholders running, I suspect the NRSC won’t intervene. But in a state like Pennsylvania, you could have a GOP primary between former hedge fund CEO Dave McCormick and 2022 gubernatorial loser Doug Mastriano. Though neither has entered the race, if that were the matchup, you could definitely see the NRSC get involved to tip the scales toward McCormick. Mastriano, a vocal denier of the 2020 election results, got blown out last November, and he would be a pushover for Democratic Sen. Bob Casey Jr.
Now, McCormick doesn’t exactly have a great track record, having very narrowly lost to Mehmet Oz in the 2022 Senate primary (Oz went on to lose to now-Sen. John Fetterman). But McCormick brings a ton of personal wealth to the table, which could help Republicans; they wouldn’t have to throw as much outside money into the race.
nrakich: Do you guys think the NRSC would be wise to intervene more, given how flawed Republicans’ 2022 Senate candidates were? It seems like, if left to their own devices, GOP primary voters often don’t pick the strongest candidates.
geoffrey.skelley: I think parties should look to intervene a fair bit if they’re worried that highly flawed Senate candidates might have a path to victory.
And in recent times — even further back to, say, 2010 — the GOP has had that problem.
Of course, when we talk about the “party,” the NRSC is just a small part of that. And the Senate Leadership Fund, a Super PAC aligned with McConnell, can spend a lot. But that’s not the whole party these days! More insurgent-minded groups like the Club for Growth might not agree with the more establishment-flavored choices the NRSC and SLF might prefer.
alex: Yes, Nathaniel, but I also think it would be wise for them to intervene because candidate quality on the Democratic side is so good. The Democrats in the toughest 2024 races are arguably among the party’s strongest. Sens. Joe Manchin of West Virginia (assuming he runs for reelection), Sherrod Brown of Ohio and Tester have all been battle-tested in their respective red states, and they’ve all overcome their states’ Republican leans — even in presidential years.
nrakich: Yeah, Alex, as you allude to, the Senate map is really bad for Democrats this cycle. They are defending eight seats in states with FiveThirtyEight partisan leans that are redder than the nation as a whole. And as a reminder, they currently have just a 51-49 majority in the Senate (thanks to three independents who align with them), so they can afford to lose only one seat if Biden and Vice President Kamala Harris win reelection. (And if they don’t, Democrats can’t afford to lose any!)
At this stage, what do you guys think are Republicans’ best opportunities to pick up those one or two seats they need?
alex: If Manchin runs for reelection, he would easily be the most endangered Democratic incumbent given that West Virginia went to Trump by nearly 40 points in 2020. When Manchin was on the ballot last, in 2018, he was able to convince Republicans to split their ticket — but I think that’ll be really hard for him next year since it’s a presidential cycle and the top of the ticket could influence his chances down-ballot. (For what it’s worth, reader, the last time he was on the ballot in a presidential year, in 2012, Manchin won by 24 points, while Republican presidential nominee Mitt Romney won the state by nearly 27. But partisan polarization has only gotten worse since then.)
geoffrey.skelley: As Alex said, West Virginia tops the charts — with a bullet. Manchin has had an incredible run winning as a Democrat in what is, along with Wyoming, the reddest state in the country. Getting enough people to split their tickets in a presidential environment isn’t going to be easy, especially if popular Republican Gov. Jim Justice is his opponent. But GOP Rep. Alex Mooney, who has aligned himself closely with Trump, is already in the race, and state Attorney General Patrick Morrisey could take another shot, after narrowly losing to Manchin in 2018.
nrakich: Yeah, our friends at Sabato’s Crystal Ball are starting West Virginia out with a “Leans Republican” rating. It’s unusual for those forecasters to put an incumbent any worse than “toss-up.”
Plus, the situation would get even worse for Democrats if Manchin doesn’t run for reelection. He’s 75 years old, and has played coy about whether he’s running again.
geoffrey.skelley: After West Virginia, the most vulnerable Democratic seats are Ohio and Montana. Tester faces a tough bid, but don’t sleep on Brown being the weaker of the two. Whereas Tester clearly outran the Democratic presidential ticket in 2012, Brown did about as well as President Barack Obama that year. And while Brown also won in 2018, he faced a very weak Republican opponent in then-Rep. Jim Renacci. So Brown may not be quite as much of an outperformer as some think.
Perhaps that’s why you could see a bevy of GOP contenders looking to challenge him.
alex: Brown is an interesting test case, Geoff, given that he’s the only Democrat to win a nonjudicial statewide race in Ohio since 2012. But between him, Tester and Manchin, I’d argue that Brown is in the best position given his populist street cred and the fact that he’s found success working with Republicans while bucking conservative trends in his state.
geoffrey.skelley: So far, Brown’s main GOP opponent is state Sen. Matt Dolan, who’s personally very wealthy (his family owns the Cleveland Guardians baseball franchise). Dolan finished a close third in Ohio’s 2022 Senate primary, running as a conservative — but not a Trumpy one. You could see some other 2022 candidates, like investment banker Mike Gibbons, run too. But some major officeholders in Ohio are also eyeing this race, and they’re the ones to watch, especially Secretary of State Frank LaRose, who could be the toughest opponent Brown has faced since first defeating Mike DeWine for this seat in 2006 (DeWine was a senator back then; now he’s governor).
alex: Yeah, Dolan hails from the more centrist wing of the party. But I’m sure he’ll have some competition in no time, so the GOP could also shoot itself in the foot again if they field a super-right-wing candidate who alienates voters there.
nrakich: OK, I think we can all agree that West Virginia, Montana and Ohio are, in some order, Republicans’ best pickup opportunities. But what other states might they have a good shot in?
geoffrey.skelley: The other Frost Belt state of note is Wisconsin, where Democratic Sen. Tammy Baldwin hasn’t yet said whether she’s running again. But assuming she does, the GOP will want to make a play for that seat too, of course. There hasn’t yet been much action there, but you might see someone like GOP Rep. Mike Gallagher decide to challenge her.
There are also a couple key seats in the southwest: Arizona and Nevada. In the latter, Democratic Sen. Jacky Rosen will face a tough reelection bid in the perennial swing state. It’s early days, but one name to watch might be Sam Brown, an Army veteran who attracted a fair amount of support on his way to finishing second, behind Adam Laxalt, in the 2022 GOP primary for Senate.
alex: I’ll definitely be keeping a close 👀 on the Arizona race, Geoff.
It has the unusual distinction of (maybe) being a three-way race: between independent incumbent Sen. Kyrsten Sinema, Democratic Rep. Ruben Gallego and the eventual Republican nominee. The fact that some early polling in the state shows that Sinema isn’t doing too hot should make it a golden opportunity.
But after two high-profile losses in Arizona in 2022 — for Senate and governor — is it not possible that Republicans blow their chances here again with a weak candidate? (I know I probably sound like a broken record at this point — forgive me, readers!) Defeated election denier Kari Lake and wealthy businessman Blake Masters are both reportedly considering a run for Senate in 2024. Those are the types of opponents that Democrats and Democratic-aligned independents alike dream of facing.
geoffrey.skelley: If you want a race where Republican bigwigs might try to get involved, it’s Arizona. If Lake and/or Masters run, they will look for a stronger alternative.
alex: That’s exactly right. If Arizona Republicans should have learned anything over the last few years, it’s that maybe they shouldn’t cater to the most extreme side of Trump’s base. 😬
geoffrey.skelley: The potential three-way dynamic of a race with an independent senator is also very hard to predict, especially this early. We don’t know that Sinema will even seek reelection — I suspect she switched from a Democrat to an independent not only to avoid a Democratic primary challenge but also in the hopes that someone like Gallego wouldn’t run and risk splitting the liberal and moderate vote.
That gambit didn’t work, though, so you have Sinema, who had more than $8 million in her campaign account at the end of 2022, potentially running third in a three-person race.
nrakich: Yeah, she has been in third place in every survey of the race I’ve seen. I wouldn’t be surprised if she just retires.
geoffrey.skelley: Historically, incumbents in her position have won when one of the major-party candidates struggled, making it more of a two-way race between the independent/third-party incumbent and the other major-party contender. But in a strongly polarized political era, I’m not sure Sinema can pull that off. She’s infuriated Democrats so much that she probably would have lost to Gallego in the primary if she had sought renomination. But she’s also a former Democratic senator, which may make an independent campaign tough to sell to Republicans.
alex: Do you think not having Sinema as their candidate will hurt Democrats’ chances of winning, though? I feel like the most straightforward path to keeping their majority is to run incumbents who are already well known to voters (despite the uphill climb a lot of them face).
geoffrey.skelley: Sinema is so unpopular with Democrats that she may not splinter the party base as much as you’d expect on paper. As OH Predictive Insights found a few weeks ago, Sinema has a better favorability rating among Republicans than among Democrats!
alex: As I said earlier, Senate incumbents rarely lose!
geoffrey.skelley: They do lose sometimes, though.
alex: But not often. 😉
nrakich: Senate incumbents also rarely leave the party they got elected with and run as independents!
geoffrey.skelley: Yeah, it’s a weird situation.
Right now, I’d expect Sinema to lose if she does run. I think having alienated much of her old party’s base makes it a tough proposition to win a three-way race. Her path to victory may be something like winning one-fifth of Democrats, one-third of Republicans and half of independents, which would give her about 35 percent of the vote. That could be enough to win a three-way race, but that scenario might be her ceiling: Is she really going to get one-third of Republicans and half of independents? I’m not so sure.
But the eventual GOP nominee will be important to that equation, and we’re a long way from knowing who that will be. (Gallego seems likely to be the Democrats’ choice.)
nrakich: OK, so that’s a lot of pickup opportunities for Republicans! Do Democrats have any realistic pickup opportunities of their own? Places where they can offset, e.g., a loss in a place like Arizona?
alex: Given the decently strong performance of Democratic Senate candidates in both Florida and Texas in 2018 (I’m looking at you, Beto O’Rourke!), incumbent Sens. Rick Scott and Ted Cruz are hardly safe. But it’s crazy to think that those two states might be the most promising pickup opportunities for Democrats next year!
geoffrey.skelley: They’re the only real takeover opportunities for Democrats, and that speaks to the difficulties the party faces in holding onto the Senate. Republicans just don’t have much turf to defend. Florida has been moving right, and while Texas has been moving left, it’s still clearly more Republican than the nation as a whole. So the GOP can mostly focus on all those seats we’ve discussed and hope their incumbents just take care of business. With Democrats holding a narrow 51-49 edge in the Senate, the GOP just needs two of three from West Virginia, Ohio and Montana, assuming there aren’t surprises. And of course, there could be surprises!
alex: Color me skeptical, and I might regret saying this come next year, but I actually don’t think that the Democrats’ Senate outlook is that dire. If Manchin runs, their chances don’t look terrible; even without him, Democrats could hang on if Republicans struggle with candidate-quality issues again. Who knows. 🤷🏽♀️