The ranks of vulnerable senators keep thinning, but that’s not helping Democrats’ chances of holding on to control of the chamber. 

Roll Call typically compiles a list of the 10 most endangered incumbents, but since our initial look at the 2024 landscape, three of those senators – Democrat Joe Manchin III of West Virginia, independent Kyrsten Sinema of Arizona and Republican Mitt Romney of Utah – have taken themselves out of contention by announcing their retirements. 

As a result, with Election Day less than six months away, just eight senators are really vulnerable. And Democrats hold the top six spots.

Republicans need a net gain of two seats to take the majority next year. And with Manchin’s departure, the GOP is all but guaranteed to pick up the seat in deep red West Virginia.

Based on conversations with campaign insiders and independent election analysts, Sen. Bob Menendez, whose trial on federal bribery and extortion charges is due to start next week, was the consensus pick for most vulnerable. 

While the New Jersey Democrat has vigorously denied the allegations, he is not running in the state’s Democratic Senate primary next month, but left the door ajar for a potential run as an independent in November. 

“I am hopeful that my exoneration will take place this summer,’’ Menendez said in a March video message.

New Jersey is a blue state and Democrats will likely keep the seat if Menendez does not run. 

So the GOP’s top targets are two Democrats from states where then-President Donald Trump easily beat Joe Biden in 2020: Montana’s Jon Tester and Ohio’s Sherrod Brown. 

Republicans will aim to tie the veteran senators to Biden, who remains unpopular in both states. Democrats contend that Tester and Brown have strong blue-collar appeal, however, that will help them withstand national headwinds.

Because this list only looks at vulnerable incumbents, it does not include competitive open seats that also will help determine control of the Senate.

Perhaps the biggest battleground race is in Arizona, where the GOP’s hopes rest with former television news anchor and failed 2022 gubernatorial candidate Kari Lake while Democrats have coalesced around Rep. Ruben Gallego. Inside Elections with Nathan L. Gonzales rates the race a Toss-Up.

In Michigan, Democratic Rep. Elissa Slotkin and Republican former Rep. Mike Rogers are the top contenders for the seat being vacated by Sen. Debbie Stabenow, though both face primaries. Inside Elections rates the race Tilt Democratic.

And in dependably Democratic Maryland, the Republicans have been buoyed by the entrance of the state’s popular former GOP governor, Larry Hogan, into the race to succeed retiring Democratic Sen. Benjamin L. Cardin. On the Democratic side, Rep. David Trone, the wealthy founder of a wine and spirits retail chain, and Prince George’s County Executive Angela Alsobrooks are battling it out ahead of an increasingly tense May 14 primary.

Here’s a rundown of the most vulnerable at this point in the race:

Menendez stays in the top spot, despite his decision not to run in the Democratic primary next month. To run as an independent, Menendez would need to submit 800 signatures by June 4. If he does so, Menendez would likely face Rep. Andy Kim, the front-runner in the Democratic primary who has perhaps helped to reshape the state’s politics in bringing a successful lawsuit to challenge a primary ballot format that gave party machines heavy influence in primaries. Menendez saw his favorability plummet after the charges against him were first announced last year, and if he is exonerated at trial, he’ll have to work to raise his ratings ahead of November.

Tester is a third-generation Montana farmer counting on his personal brand to provide an edge in a state that has grown increasingly unwelcoming to Democrats. He’ll face former Navy SEAL and businessman Tim Sheehy, who picked up Trump’s endorsement and received a boost in February when his top GOP rival, Rep. Matt Rosendale, dropped his bid. Republicans have sought to portray Tester as a D.C.-insider and a favorite of lobbyists while Democrats say Sheehy is an untested rich guy whose life story will now be under a microscope. At the end of the first quarter, Tester had about $12 million in his campaign account, compared with $1.9 million for Sheehy.

Even Republicans acknowledge that Brown is a tough competitor who’s managed to hold on to the seat despite Ohio’s move away from the Democratic Party. With almost $16 million on hand, Brown, the chairman of the powerful Senate Banking Committee, has the largest war chest of any Senate candidate running in a Toss-up district this year. His Republican opponent, Trump-backed businessman Bernie Moreno, had about $1.8 million on hand. Moreno won a bruising primary against two other Republicans and has endured criticism for his business dealings while Republicans say Brown walks in lockstep with Biden.

Rosen remains among the most vulnerable ahead of Nevada’s June 11 primary, when she will learn whether the candidate backed by the National Republican Senatorial Committee, Sam Brown, is in fact her challenger. Brown released polling last month showing him with a commanding lead in the primary, but Trump has not made an endorsement. The other notable names on the GOP ballot are Jeff Gunter, who was Trump’s ambassador to Iceland, and recurring candidate Jim Marchant. Rosen had $13.2 million in cash on hand at the end of the first quarter, with Brown having $2.3 million. Gunter, who raised $600,000 and put in another $2.7 million of his own, had $2.6 million.

The three-term Democrat is locked in a tough reelection battle against Dave McCormick, a former hedge fund CEO who officially became the Republican nominee last month. Casey had $11.9 million on hand on April 3, while McCormick had $6.4 million, but McCormick could add to the $2 million he’s already contributed to the campaign. A super PAC supporting McCormick, Keystone Renewal PAC, had raised $21 million as of April 3. Both candidates are already up on air. Democrats have questioned McCormick’s business dealings and his residency, while Republicans have sought to tie Casey to Biden, a Pennsylvania native whose own reelection could hinge partly on his results here. 

Baldwin spent last year preparing for the election without an official opponent, but that changed in February when businessman Eric Hovde entered the race. He’s put $8 million into his campaign and he’s been spending it, according to FEC reports. Hovde had $5.3 million on hand at the end of March compared to Baldwin’s $10.3 million. Both parties expect this race to be much closer than Baldwin’s 11-point win in 2018, especially with the competitive presidential race, but Baldwin begins with higher name ID than Hovde, who lost a 2012 Republican primary for Senate. Still, an April Marquette Law School poll found the two 50-50 among likely voters. 

Cruz is a conservative firebrand with proven ability to raise money. But Rep. Colin Allred, his Democratic opponent, had $10.5 million at the end of the 1st quarter while Cruz had $9.3 million. This is the first election Cruz has faced since he endured criticism for traveling to Cancun when a devastating ice storm struck the state in 2021. Allred, a Dallas-area Democrat who was an NFL linebacker and served in the Obama administration, has also accused Cruz of spending more time podcasting than serving his constituents. But Cruz remains a formidable opponent: A poll conducted in April by the University of Texas and the Texas Politics Project found him leading Allred by 13 points.

Scott’s state has become more Republican since he narrowly flipped the seat six years ago. And he has shown no hesitation about using his personal wealth in elections, having already loaned his campaign $7 million through March 31. Democrats backing former Rep. Debbie Mucarsel-Powell hope a referendum on abortion access will bring voters out. As head of the Senate GOP’s campaign arm in 2022, Scott pitched a platform that called for all federal programs to be reauthorized every five years. After intense criticism, he revised the plan to exempt Social Security and Medicare, but Democrats are sure to keep using the issue in attack ads aimed at the state’s large retiree population.

Dave McCormick’s campaign account cash on hand total and the date of his and Bob Casey’s most recent disclosure is updated in this report.

Niels Lesniewski and Herb Jackson contributed to this report.