Multiple Republican candidates in swing-state races aligned themselves with former President Donald J. Trump after he said abortion access should be left up to the states, avoiding mention of a national ban and laying bare the party’s rift over the issue.

The pivot was particularly pronounced among several G.O.P. contenders for the U.S. Senate, which Democrats control by a razor-thin 51-49 seat majority.

Republicans would need to flip just one seat in the chamber if Mr. Trump prevails in the November election, but have watched the losses pile up for the party’s candidates since the Supreme Court overturned Roe v. Wade in 2022. In the midterm elections that year, a widely predicted “red wave” failed to materialize for Republicans, who missed opportunities in Pennsylvania, Nevada and Arizona to flip the Senate and dropped key governor’s races, including in Michigan.

“I agree with President Trump that the issue of abortion should be decided at the state level,” Mike Rogers, a former longtime House member from Michigan whom Mr. Trump endorsed in that state’s open-seat U.S. Senate race, said in a statement.

As a House member in 2013, Mr. Rogers was one of 131 Republican co-sponsors of the Life at Conception Act, a fetal personhood bill that did not pass.

Kari Lake, a Republican who is running for the U.S. Senate in the battleground state of Arizona after her failed bid for governor in 2022, also fell in line with Mr. Trump.

“I agree with President Trump: I do NOT support a federal abortion ban, policy should be up to individual states,” she wrote on Monday on X.

In Ohio, Bernie Moreno, a wealthy former car dealer who rode Mr. Trump’s endorsement to a victory last month in a hotly contested Republican primary for the Senate, staked out similar ground.

“Bernie has always said it should be primarily decided at the state level,” Reagan McCarthy, communications director for Mr. Moreno’s campaign, said in an email. “He’s comfortable with any path forward that ends elective, late-term abortions with reasonable exceptions and saves as many babies as possible.”

Senator Josh Hawley of Missouri, who is running for re-election in a race that the nonpartisan Cook Political Report classified as a “solid Republican” seat, also endorsed a state-by-state approach.

“We don’t have a national referendum system so the way voters get to vote, is they’re going to vote in the States,” he told reporters on Monday on Capitol Hill. “I just see this as a voter issue. And to be clear, I’m pro-life. I’m going to argue for pro-life laws. If I get the chance to vote in my state, I’m going to vote for what I think is the most pro-life position with exceptions for rape, incest, life of the mother.”

Robert Jimison contributed reporting from Washington. D.C.