Senate Republicans still savoring their newfound majority will have to soon pivot to the challenge of keeping that control in two years when they face a more competitive map.
Republicans will be defending nearly two-thirds of the Senate seats on the ballot in 2026. At the same time, GOP gains last week coupled with a battleground map more evenly divided gives Republicans hope they can limit the kind of defeats that historically occur in midterm elections when the president is of the same party.
With the House also narrowly divided, the loss of GOP control on Capitol Hill would likely doom most of President-elect Donald Trump’s agenda. The loss of the Senate would also make it difficult for Trump to push through judicial and other nominees.
“If this follows history and in Trump’s second term his approval ratings are low and we see a backlash to the incumbent party, that would absolutely boost Democrats and could put the majority more in play,” said Jessica Taylor, the Senate and governors editor for The Cook Political Report with Amy Walter.
But she warned flipping the Senate “is hard to do when you look at the 2026 map.” Democrats are defending seats in blue states which showed shifts toward Republicans last week. Republicans will have a 53-47 majority, meaning Democrats will have to pick up four seats.
All 13 states with Democratic senators up for re-election next cycle voted for President Joe Biden in 2020. But Trump’s victories in Michigan and Georgia this year signal Sens. Gary Peters (D-Mich.) and Jon Ossoff (D-Ga.) could face more competitive races.
“Two years of a Republican agenda is good, but four years of success under Donald J. Trump is even better,” Sen. Tim Scott (R-S.C.), the only declared candidate to helm Senate Republicans’ campaign arm next cycle, said.
Competitive Seats
Sen. Susan Collins (R-Maine) could be vulnerable this cycle. Maine has favored Democratic candidates the last nine presidential elections, though Collins won her last term by 9 points and remains well liked in the state.
Collins, who is line to chair the Appropriations Committee, typically announces her intentions late in the cycle.
Other GOP senators seeking third terms are Sens. Thom Tillis (N.C.) and Joni Ernst (Iowa).
Tillis told reporters in September he plans to run for re-election in a swing state that split its vote between Trump and Democratic Gov.-elect Josh Stein, who soundly defeated scandal-ridden GOP nominee Mark Robinson.
Rep. Wiley Nickel (D-N.C.), who opted out of seeking re-election, said in an interview he’s preparing to run for Senate with an announcement tentatively planned for February.
Voters want lawmakers “focused on getting things done” in contrast to “MAGA extremism” that is “taking our state in the wrong direction,” said Nickel.
Sen. Jeanne Shaheen (D-N.H.), 77, declined to comment on her 2026 plans back in September. But her state kept the governor’s office in Republican hands even as it backed Vice President Kamala Harris’s White House bid, so a potential retirement could put the state in play.
Sen. John Hickenlooper (D) plans to seek a second and final term in Colorado, where Harris beat Trump, after unseating a Republican incumbent in 2020.
Turnover by Retirement
Republicans could see turnover in some states without risking partisan flips. Outgoing Senate Minority Leader Mitch McConnell has not said since he announced plans to leave leadership whether he’ll seek an eight term in heavily Republican Kentucky.
Ohioans should also expect a special election in 2026 for the remainder of Vice President-elect JD Vance’s Senate term. Gov. Mike DeWine (R) has the power to appoint a replacement who would likely compete in that contest in an increasingly red state.
Republicans will also be defending a seat in Florida if Sen. Marco Rubio becomes secretary of State. The GOP would be favored to win that special election as the former swing state has shifted to the right, especially if Gov. Ron DeSantis’s anticipated appointee runs to finish out the six-year term.
Sen. Bill Cassidy is the only other Republican besides Collins on the ballot in 2026 who voted to convict Trump in his second impeachment trial, creating the possibility he would face an intraparty challenger in deep-red Louisiana.
“I actually voted more with President Trump than did” Sen. John Kennedy (R-La.), Cassidy said.
Democrats could see retirements as well. Senate Majority Whip Dick Durbin, who turns 80 next week, has previously said he’ll decide next year if he’ll seek a sixth term. His retirement could pave the way for an aspiring House member or state-level official to represent deep-blue Illinois.
But Sen. Ed Markey (D-Mass.), 78, left no doubt of his future plans after dispatching a vigorous primary challenge by then-Rep. Joe Kennedy (D-Mass.) four years ago: “I’m running again,” he said in an interview.
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