Some of President-elect Donald J. Trump’s closest allies are privately counseling him to try to block a onetime Republican nemesis from becoming the Senate majority leader, pushing him to impose his will more forcefully on an already compliant G.O.P. Congress.
Those advisers believe Mr. Trump should stop Senator John Thune of South Dakota, the No. 2 Republican, from winning the top post, according to people familiar with the talks. One person close to the president-elect noted that he had not weighed in on the race.
Doing so would be an extraordinary move even for Mr. Trump, who during his first term and since he has left office has had an iron grip on congressional Republicans. He has demanded and almost always received loyalty from them on matters of policy and personnel.
Mr. Thune, an establishment Republican who is reviled by some on the MAGA right, is competing for the position against Senators John Cornyn of Texas and Rick Scott of Florida. Republican senators and senators-elect are set to vote by secret ballot on Wednesday.
Intervening in an internal leadership struggle among G.O.P. senators, who have at times been more resistant to the former president’s dictates and where members are fiercely protective of their independence, would signal Mr. Trump’s determination to dominate the legislative branch in his second term. The majority leader controls the Senate floor, including what proposals and nominees receive votes, and when.
Mr. Trump has already indicated his desire to hold a tighter rein on the Senate in the days since he was elected. He posted an ultimatum on social media on Sunday in which he demanded that any new Senate leader cooperate in his efforts to circumvent the confirmation process by calling recesses during which he could appoint personnel without winning Senate approval. All three candidates vying to lead the Senate next year quickly promised to speed through his choices.
