Former President Donald Trump has gotten his most high-profile endorsement from a Senate Republican yet, winning the backing of Montana’s Steve Daines, chief of the Senate’s GOP fundraising arm.

“I’m proud to endorse Donald J. Trump for president of the United States,” Daines, chair of the National Republican Senatorial Committee, said Monday night on a podcast hosted by Trump’s eldest son, Donald Trump Jr.

The endorsement is Trump’s first from a Republican in Senate leadership and could help open up support from others in the chamber. The former president has a frosty relationship with GOP leader Mitch McConnell of Kentucky, but a number of other senators have already backed his 2024 run, including Lindsey Graham of South Carolina, Marsha Blackburn of Tennessee and JD Vance of Ohio.

GOP Field Continues to Grow

As NRSC chair, Daines is tasked with helping his party regain control of the chamber. He has indicated he intends to make some changes after Republicans’ underperformance in last year’s midterm elections, when then-NRSC Chair Rick Scott of Florida insisted on remaining neutral in nominating contests and a number of far-right candidates won their primaries, only to lose in the general election.

Daines’ new approach would mean wading into party primaries in key states and providing resources to preferred candidates to help produce nominees who are more palatable to general election voters.

As the GOP field continues to grow, Trump has been lining up endorsements to show the strength of his support in the party. He has already won the backing of more than half of the House Republicans in Florida, notable because the state’s governor, Ron DeSantis, is considered a top potential rival to Trump for the nomination.

Former Arkansas Gov. Asa Hutchinson this week officially kicks off his GOP bid, joining Trump, former U.N. Ambassador Nikki Haley, biotech entrepreneur Vivek Ramaswamy, businessman Perry Johnson and radio host Larry Elder. Sen. Tim Scott of South Carolina, former Vice President Mike Pence and former New Jersey Gov. Chris Christie have said they’ll decide whether to mount their own campaigns in the coming weeks.

With primary season still months away, a possible general election matchup also began to take shape Tuesday, with Democratic President Joe Biden formally announcing he’d be seeking a second term. In his video announcement, he asked voters to give him more time to “finish this job.”

During a Monday night interview on Newsmax, Trump said Biden’s bid “seems hard to believe” but poked at the Democratic incumbent for unveiling his reelection bid in a video rather than at a live event.

“You know, normally you get up and you say, ‘Hey, I’m running. Wish me luck, everybody.’ But he’s doing a tape,” Trump said. “You can do it four or five times so he gets it right.”