WASHINGTON — Senate Republicans vying to replace longtime leader Sen. Mitch McConnell have been crossing the country to campaign and fundraise for colleagues, making their final arguments before a consequential ballot the week after the presidential election.

But their pitches are mostly behind closed doors, and most GOP senators won’t yet say which lawmaker they are backing.

South Dakota’s Sen. John Thune, McConnell’s current No. 2, and Sen. John Cornyn of Texas, who held that job before Thune, are the front-runners in the Nov. 13 secret ballot to replace McConnell. The Kentucky senator is stepping aside from the post in January after almost two decades as leader.

The winner could steer the direction of the party for years to come and possibly become the next Senate majority leader if Republicans win enough seats in Tuesday’s election.

The outcome is, for now, uncertain.

Only a few Republican senators have publicly endorsed a candidate. Many say they are still undecided. The third senator in the race — Florida Sen. Rick Scott, who is dealing with his own reelection bid — could act as a spoiler. And another candidate could still jump in.

In many ways, “the two Johns” are remarkably similar, making the choice difficult for their colleagues. Both are well-liked and, in the mold of McConnell, lean toward the more traditional wing of the Republican Party.

But both have also suggested they will try to move on from the McConnell era with a more open approach.

“I’m trying to find differentiation because they’re both great guys,” said Sen. Thom Tillis, R-N.C., who has worked closely with both of them.

The two men are also trying to distinguish themselves from McConnell by making clear that they support Donald Trump in this year’s presidential election. Like McConnell, they have both sparred with Trump in the past, especially after the Jan. 6, 2021, attack on the Capitol.

But both Thune and Cornyn have talked to Trump frequently in recent months, attended campaign events and visited his Florida home.

Whether Trump wins, and if he endorses one of the contenders, could become a determining factor.

“I don’t know what he’ll do,” Cornyn said of Trump in September. “But this is obviously an election between senators, and I think that’s where the voters are.”