Which Senate seats could flip in 2024? The races to watch

The Democratic Party holds a narrow majority in the U.S. Senate, but 34 out of 100 seats are up for election on Nov. 5, which may result in a power shift.
Seats in eight of the most competitive races, including Montana, Nevada, Arizona, Texas, Wisconsin, Michigan, Ohio, and Pennsylvania could be tossups that tip the balance of power in Capitol Hill’s upper chamber.
Democrat Jon Tester has served three terms in the Senate representing Montana. He has fended off a challenge from Trump-endorsed Republican businessman Tim Sheehy. The New York Times reports that Tester’s “victories in 2006, 2012 and 2018 all came in strong Democratic cycles. His fight for a fourth Senate term will be considerably tougher. According to CNN, Tester is “the most vulnerable Senate incumbent,” but that “Democrats still see a path to victory.”
Senator Sherrod Brown, a three-term Democrat in the red state of Ohio, is also trying to hold onto his seat in a tight race against a wealthy businessman endorsed by former President Donald Trump. Republican candidate Bernie Moreno is not faring as well as Sheehy is in Montana, though the Buckeye State race is far from safe for Brown.
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CNN reported that the campaign is “the most expensive congressional race on record,” spending nearly $450 million.
Democrat Bob Casey, who has represented the Keystone State in the U.S. Senate since 2007, is campaigning against Republican challenger David McCormick, a former hedge fund executive.
Polls dating back to September, including from The New York Times/Siena College and Marist College, show Casey consistently ahead by at least several points. However, both candidates are campaigning hard over issues including abortion, inflation, and immigration.
CNN calls Michigan’s U.S. Senate race “the most competitive open seat” in its top 10. Incumbent Democrat Debbie Stabenow is retiring, leaving an open seat that Democratic U.S. Rep. Elissa Slotkin and Republican former Rep. Mike Rogers are vying for.
Both candidates are spending a lot of money on campaigns centered on the issues of abortion, electric vehicle manufacturing, and their ties to their party’s presidential nominees, according to CNN and Time.
In Arizona, Democrat Ruben Gallego is leading by up to double digits against Republican Kari Lake in a race to fill the seat left vacant by retiring Sen. Kyrsten Sinema, who is an independent but caucuses with the Democratic Party. According to polling averages from 538, Lake is lagging behind Trump in Arizona.
Time reports that the high number of independent voters in the state will likely be the determining factor in the outcome of the race.
CNN reports that reelection for incumbent Democrat Jacky Rosen is a more substantial bet against Republican challenger Sam Brown than earlier this year, but that the race is still eighth in its top ten closest Senate races. Time reported that Rosen’s strong fundraising and pro-choice messaging in a state with an abortion measure on the ballot have helped her odds.
The Lonestar State’s Senator Ted Cruz is currently facing a tough re-election challenge that The Hill compared to a campaign by Beto O’Rourke campaign to unseat him six years ago. U.S. Rep. Colin Allred may be a long shot in red Texas but could benefit from Cruz’s low approval ratings and the Democrats’ significant ad spending, as reported by CNN and Newsweek.
Polling for Wisconsin incumbent Democrat Tammy Baldwin, the first openly gay U.S. Senator, shows her leading over Republican challenger Eric Hovde. CNN reported that he has put $13 million of his own money into the race, which CNN called Baldwin’s “most competitive reelection.”
While his self-funding is a strength, Democrats have also used it to attack him as “out of touch with Wisconsin values,” according to Time.