Matt Rosendale to Run for Senate in Montana, Igniting Republican Fight

Representative Matt Rosendale of Montana is expected to announce a campaign for Senate as soon as this weekend, torching plans from top Republican officials to avoid a bruising primary battle in a state that many in the party view as their best chance to win back control of the chamber.

Mr. Rosendale, an anti-abortion Republican agitator who voted to overturn the 2020 election, plans to formalize his campaign as Montana Republicans gather for their winter meetings this weekend in Helena, according to three people familiar with the deliberations who insisted on anonymity to discuss unannounced plans. A spokesman for Mr. Rosendale declined to comment.

Awaiting the results of the Republican primary is Senator Jon Tester of Montana, a Democrat seeking his fourth term. Mr. Tester is a top target for Republicans given Montana’s deep-red political complexion: Former President Donald J. Trump won the state by more than 16 percentage points in 2020.

More traditional Republican leaders in Washington are pushing the already-announced candidacy of Tim Sheehy, a wealthy businessman seen as a more palatable choice for moderate voters in the general election.

Mr. Tester’s fellow Montanan in the Senate, Steve Daines, has tried to clear a path to the nomination for Mr. Sheehy from his role as chairman of the National Republican Senatorial Committee, the campaign arm for Senate Republicans.

Mr. Daines has helped Mr. Sheehy secure a lengthy list of endorsements from Republican lawmakers across the party’s political spectrum, including Senator John Barrasso of Wyoming, who holds the No. 3 position in Senate Republican leadership, and Representative Marjorie Taylor Greene, the Trump superfan from Georgia.