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Which senators still undecided about 2024 runs will matter most?

Manchin choice may have biggest impact on party control

Sen. Joe Manchin may be the only Democrat who could win in West Virginia next year, so his decision whether to run again has a big impact on the fight for party control.
Sen. Joe Manchin may be the only Democrat who could win in West Virginia next year, so his decision whether to run again has a big impact on the fight for party control. (Tom Williams/CQ Roll Call file photo)

ANALYSIS — A batch of reelection announcements over the past few weeks helped bring the battle for the Senate into focus. But there are still a few senators who haven’t revealed their decision to seek another term, including Democrat Joe Manchin III of West Virginia, whose decision will have the most significant impact on the battle for Senate control. 

Up to this point, there haven’t been a lot of surprises.  

There are currently three open seat races. Republican Sen. Mike Braun of Indiana is running for governor and GOP Rep. Jim Banks is the clear front-runner to replace him, even though the primary is still more than a year away. Eighty-nine-year-old Democratic Sen. Dianne Feinstein is not running for reelection in California, but Democrats shouldn’t have trouble holding her seat. And Democratic Sen. Debbie Stabenow is not running again in Michigan, where Democrats have a narrow advantage in neutral conditions.

In January, there were a few hours of drama surrounding Democratic Sen. Tim Kaine’s future, but he announced for reelection. 

Sen. Sherrod Brown announced his reelection bid way back in November, which is good for Democrats since he’s probably the only Democrat who can win statewide in Ohio right now. Democratic Rep. Tim Ryan was widely praised for his 2022 Senate bid, and he still lost by 6 points to a Republican running an underwhelming campaign. 

Similarly to Ohio, Sen. Jon Tester is one of the only Democrats who can probably win statewide in Montana right now. He announced his reelection campaign in February. 

Massachusetts Sen. Elizabeth Warren announced her reelection bid for a third term on March 27, even though she initially misspoke and told MSNBC host Lawrence O’Donnell that she was running for president. Old habits die hard, I guess. 

Warren’s decision wasn’t a surprise (particularly since she actually mentioned it in May of 2021), and she should have an easy path to reelection. It would be shocking if former GOP Gov. Charlie Baker ran against her. He’s still settling into his new job as president of the NCAA and he would likely struggle in a federal contest (if he could win a GOP primary), even though he received high marks from Democrats as governor. Voters make different calculations when control of the Senate is on the line. 

More recently, Sens. Jacky Rosen of Nevada, Tammy Baldwin of Wisconsin, and Bob Casey of Pennsylvania all announced their reelection bids in what should be a trio of competitive races. Based on the resiliency of Democratic incumbents in 2022, this is good news for Democrats trying to hold onto their narrow majority in 2024. Republicans need a net gain of two seats for the Senate majority, or a net gain of just one seat for control of the Senate if they also win the White House because the new vice president could break tie votes. 

Still, a handful of senators have not announced their 2024 intentions yet. 


Even though he’s won six statewide elections in West Virginia, Manchin is arguably the most vulnerable senator in the country. He told NBC in early April that he wouldn’t decide whether to run for reelection until the end of the year. The filing deadline is in January. 

That seems very late for one of the most vulnerable senators, particularly as GOP Gov. Jim Justice moves closer to getting into the race. Even though Manchin had $9.7 million in his campaign account at the end of March, it’s hard to imagine Democrats giving Justice a head start in full campaign mode. 

If Manchin does run again, he’s not guaranteed to win. West Virginia has shifted significantly since he was last on the ballot. Manchin was reelected in 2018 by just 3 points and with less than 50 percent of the vote against a flawed opponent, state Attorney General Patrick Morrisey, when West Virginia’s Democratic Baseline was 45.4 percent. But that Baseline dropped to 37.6 percent following the 2022 elections. If Manchin overperforms by the same amount in 2024 as he did in 2018, he’d fall short of 42 percent and likely lose reelection. If Manchin doesn’t run again, it’s a likely pickup for Republicans.


Independent Kyrsten Sinema of Arizona is the other high profile senator who has not announced a reelection decision. 

A couple weeks ago, the Wall Street Journal published details of a slide deck from a recent staff retreat that included a timeline for the senator’s reelection announcement. It called for getting a poll and opposition research done by the end of September and staffing up by the end of the year. But the slide deck doesn’t mean she’s running again. It’s just something you should be doing to put yourself in a position to run. 

Sinema has some time, considering the filing deadline isn’t until next April. But it will take more time and money than usual to get on the ballot as an independent. According to the Journal, she’ll need to gather an estimated 40,000-plus signatures from nonaffiliated voters.

Unlike Manchin, Tester, and Brown, Sinema’s decision isn’t as consequential to Democratic efforts to hold the Senate majority. Her presence complicates the race, but she’s not essential to a Democratic victory. Her own path to victory looks limited considering she’s not popular among Democrats or Republicans, and there’s no guarantee she’ll draw disproportionately from either of the two major party nominees.


Democratic Sen. Ben Cardin’s meager first-quarter fundraising fueled rumors that he won’t seek reelection in Maryland. He raised just $15,000 in the first three months of the year and had just shy of $1 million in his campaign account. If he runs, he’s not likely to face serious opposition, but the open seat would create some uncertainty with a competitive Democratic primary. 

Republicans would love for former Gov. Larry Hogan to run. He was popular among Democrats as an inoffensive governor, but federal races with control of the Senate on the line are different, and Hogan might have trouble in a Republican primary as well. And it appears that Hogan has his hopes for higher office, including president at some point (not in 2024, though). 

In the end, Democrats are likely to hold Maryland with or without Cardin. The only question is whether it’s an open seat race or not. 


 At 51 years old, Democratic Sen. Martin Heinrich is still younger than more than 80 of his Senate colleagues. But it’s not clear whether he’ll seek a third term. 

If Heinrich chooses not to run, Democrats would still be favored to hold the seat. Joe Biden won New Mexico by more than 10 points in 2020, the same cycle Democratic Rep. Ben Ray Lujan won an open seat race for the other U.S. Senate seat by 6 points. 

Overall, Democrats have a 54.9 percent to 43.3 percent Baseline advantage in New Mexico. But Republicans will try to field a strong recruit to force Democrats to spend money defending yet another seat.


Democratic Sen. Thomas R. Carper has yet to announce his plans as well and after Cardin, he had the lowest fundraising total among Democrats whose terms are up next year, raising just $195,000 in the first quarter. The 76-year-old incumbent has held public office in Delaware since Jimmy Carter was president.

If Carper decides not to run for a fifth term, Democratic Rep. Lisa Blunt Rochester would be the favorite to succeed him. She already represents the entire state as the at-large representative, and a woman of color, with her resume, would be hard to beat in a Democratic primary. General elections in Delaware are more of a formality these days.

Nathan L. Gonzales is an elections analyst for CQ Roll Call.

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