Trump Endorsed by Senator Daines of Montana, a Key Republican Fund-Raiser

Former President Donald J. Trump has secured one of his most important Capitol Hill endorsements for a 2024 presidential bid: Senator Steve Daines of Montana, the chairman of the Senate Republicans’ campaign arm.

While top Republicans in the Senate have been lukewarm about the prospects of another election cycle dominated by Mr. Trump, the endorsement gives him a foothold with a key party fund-raiser.

“I’m proud to endorse Donald J. Trump for president of the United States,” Mr. Daines said during a Monday night appearance on “Triggered,” the podcast of Donald Trump Jr., the former president’s eldest son and an occasional hunting buddy for Mr. Daines.

He added that the “best four years” he’d had in the Senate was when Mr. Trump was president. And Mr. Daines ticked off a list of accomplishments that he said Mr. Trump had recorded, on issues like immigration.

“That’s absolutely awesome,” Mr. Trump Jr. replied.

Mr. Trump has notched a string of congressional endorsements, but Mr. Daines, the chairman of the Senate campaign arm, the National Republican Senatorial Committee, has outsize influence. Mr. Daines is in constant contact with the wealthiest donors in Republican politics, who have been reluctant to support Mr. Trump, even as he asserts himself as the clear front-runner less than a year out from the primaries. If Mr. Daines vouches for the former president as he works the donor circuit, it may bolster what has been until now fairly lackluster fund-raising from the Trump campaign.

Mr. Trump and Senator Mitch McConnell, the Republican leader, are not on speaking terms, and his supporter in the Senate with the most seniority was Lindsey Graham of South Carolina.

Yet for Mr. Daines, the decision was a relatively safe move. With a closer relationship, Mr. Trump could support the Senate candidates backed by Mr. Daines’s committee — or at least avoid attacking the committee’s preferred candidates. Mr. Daines’s relationship with Mr. Trump Jr. is also seen as an important conduit between the Senate and the Trump operation.

Mr. Daines and Mr. Trump Jr. began the interview bantering about their past hunting trips but Mr. Daines eventually spoke of how Republicans have a “once a decade” opportunity to pick up seats with a favorable map in 2024. If Republicans failed, he warned, they could remain in the minority “for the rest of the decade.” Before he endorsed Mr. Trump, during the interview, Mr. Daines talked about the power that strength at the top of the ticket could mean in the Senate races.

Mr. Trump’s chief rival for the nomination, Gov. Ron DeSantis of Florida, has faced some difficulty connecting with potential supporters as he works toward making his candidacy official. Both hopefuls have pushed for endorsements in Congress. While Mr. Trump has collected dozens, Mr. DeSantis, a former congressman, has secured just a handful. The people endorsing Mr. Trump have been quick to praise his personal touch.

In the 2022 cycle, the National Republican Senatorial Committee, under the chairmanship of Senator Rick Scott, took a largely hands-off approach to the primaries. Mr. McConnell lamented the “candidate quality” of those who had emerged from primaries, and several Republicans aligned with Mr. Trump went on to lose key battlegrounds in November, including Don Bolduc in New Hampshire and Blake Masters in Arizona, both of whom party strategists had predicted would be weak nominees.

Mr. Daines has taken a different approach. He has endorsed Representative Jim Banks for an open Senate seat in Indiana and has courted other candidates, including David McCormick, the former hedge fund executive who lost a Senate primary in Pennsylvania last year, to run again.

Still, Senate Republicans are facing a gantlet of potential 2024 primaries, and the party leadership is worried that weak potential candidates could yet again hinder Republicans in November, including in Mr. Daines’s home state, Montana.

In West Virginia, for instance, national Republicans have wooed Gov. Jim Justice, a billionaire former governor, to run against Senator Joe Manchin III, a Democrat who faces a tough re-election fight in a state that Mr. Trump won overwhelmingly in 2020. Mr. Justice is expected to enter the race on Thursday, but Representative Alex X. Mooney, who won a fierce Republican primary in 2022 with Mr. Trump’s endorsement, has already entered the contest.

Other states that may feature thorny Republican primaries include Arizona, where the former television newscaster Kari Lake, who lost her 2022 bid for governor, may run for Senate in 2024, and Pennsylvania, where Doug Mastriano, who badly lost a 2022 governor’s race, is looking at a Senate run.

“The primary is ours to walk away with,” Mr. Mastriano said in an interview on Monday with the conservative radio host John Fredericks. “We have the base. We are the base.”

Mr. Mastriano is the type of nominee Mr. Daines is seeking to avoid. “His last race demonstrated he can’t win a general,” Mr. Daines said last month.