Some of President-elect Donald 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 GOP Congress.

Trump has been considering the counsel of advisers who believe he should join an effort on the right to stop Sen. John Thune of South Dakota, the No. 2 Republican, from winning the top post, according to people familiar with the talks who insisted on anonymity to discuss them, though 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 Trump, who during his first term and since he has left office has had an iron grip on congressional Republicans, demanding and almost always receiving loyalty from them on matters of policy and personnel.

Intervening in an internal leadership struggle in the Senate, which has at times been more resistant to the former president’s dictates and where members are fiercely protective of their independence, would signal 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.

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 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.

Republican senators and senators-elect are set to vote by secret ballot Wednesday on who should serve as majority leader in the next Congress. Thune, an establishment Republican who like Sen. Mitch McConnell of Kentucky, the current leader, is reviled by some on the MAGA right, is competing against Sens. John Cornyn of Texas and Rick Scott of Florida.

Trump has not lent his voice to the bid to block Thune, but influential figures in his orbit are pushing a campaign to do so. They include former Fox News host Tucker Carlson, Trump’s former chief strategist Steve Bannon and right-wing influencer Charlie Kirk. Most of them are instead supporting Scott, whom Trump backed two years ago when he challenged McConnell.

But Trump is said to have privately conceded that Scott, who is unpopular with his colleagues, has little chance of succeeding in his bid. (The Floridian received only 10 votes the last time he sought to lead his GOP colleagues.) One person close to Trump said the president-elect was reluctant to get involved in the leadership fight unless he is certain he has the votes to push the winner over the line.

For months, Thune and Cornyn have been seen as the front-runners in the race to succeed McConnell. Each has crisscrossed the country raising millions of dollars for other senators and shoring up votes privately.

Thune and Cornyn, both institutionalists, have worked to improve their relationships with Trump, who has been harshly critical of each at different times but has stayed out of the fray during this leadership contest. Thune visited Mar-a-Lago in Palm Beach, Fla., in March and spoke with Trump just days ago. Cornyn has met with Trump twice in recent months, in Texas and Nevada, and also speaks with him regularly.

Both have run quiet, traditional races, working in one-on-one meetings with senators to secure votes, pitching themselves as experienced leaders who can navigate the intricacies of Congress to deliver on Trump’s legislative agenda. Thune is believed to have an edge over Cornyn.

Scott, by contrast, is running to appeal to the right flank of the party, and doing so publicly and online. Many in the establishment wing of the party view Scott’s time leading Senate Republicans’ campaign arm as a failure.