The things Todd Blanche did to persuade President Trump to nominate him as attorney general might be the things that prevent him from being confirmed as attorney general.

Mr. Blanche, the acting attorney general and the former leader of Mr. Trump’s criminal defense team, has been a faithful executor of the president’s campaign of retribution and a guardian of the president’s interests. As a top official at the Justice Department, he embraced a damage-control role behind the scenes during the release of the Epstein files.

Earlier this year, when asked how he would respond if Mr. Trump fired him, Mr. Blanche replied, “I love you, sir.”

But Mr. Blanche’s audience-of-one approach, which got him to where he is now, has collided with the jury-of-two reality in the Senate that has, thus far, kept him from the prize he covets: the stability and status conferred by a Senate confirmation.

Two Republicans on the Senate Judiciary Committee, Senator John Cornyn of Texas and Senator Thom Tillis of North Carolina, are blocking his path to a floor vote over concerns about a deal Mr. Blanche signed to resolve Mr. Trump’s lawsuit against the I.R.S. It created a $1.8 billion fund for purported victims of prosecutorial abuses and included a provision that would grant sweeping tax immunity to Mr. Trump and his family.

That puts Mr. Blanche in the crossfire between the holdouts and Mr. Trump, who on Thursday floated the idea of temporarily withdrawing his nomination, seemingly unwilling to give away a tax shield that could result in a $100 million windfall to secure the confirmation of a man who has pledged his loyalty to him.

“I can see why he wants it, because it provides immunity from audits that no other taxpayer could possibly get,” a grinning Mr. Cornyn said when asked about Mr. Trump’s motivations this week.

But the battle is far bigger than Mr. Blanche, who will be able to serve indefinitely in an acting capacity even if his nomination flops. It represents the first serious revolt by Republicans against Mr. Trump’s extraordinary transformation of the Justice Department from an independent institution to an extension of presidential will overseen by a team of his former personal lawyers who must serve his interest to keep their jobs and get promotions.

After more than a year and a half of allowing Mr. Trump and his appointees to work their will with almost no pushback, Senate Republicans appear weary of being force-fed politically radioactive proposals concocted by Mr. Trump, and somewhat more willing to question the way the department is being run.

The two senators standing in Mr. Blanche’s path can afford to resist because they are nearly out the door. Mr. Cornyn and Mr. Tillis are both retiring after the midterms, after their clashes with Mr. Trump’s actions resulted in his withdrawal of support, which proved politically fatal.

But both have said they represent a much larger group of Senate Republicans who have reservations about the implications of the tax deal, but do not want to incur the political risk to publicly side with them.

“There are more than just two people who have reservations about the weaponization fund and about the scope of the settlement decree,” Mr. Cornyn told reporters on Thursday, after a scheduled vote on Mr. Blanche’s nomination was delayed for lack of “yes” votes.

Mr. Blanche reacted as he often does when confronted with an impasse. He huddled with his team to find a solution, trading written proposals with Mr. Cornyn’s office, including language that mirrored his public claims that the anti-weaponization fund was dead, according to people familiar with the talks. It was unclear if he was authorized to revise the tax deal.

Mr. Trump reacted as he always does when challenged by members of his own party. He lobbed digital thunderbolts on Truth Social.

On Thursday, he attacked Mr. Cornyn as a sore loser who was exacting vengeance after Mr. Trump endorsed a successful challenger in the Republican primary this year. Then he suggested he would consider “temporarily” withdrawing Mr. Blanche’s name “and putting him back after Cornyn and Tillis are out of office.”

(Mr. Cornyn quickly pointed out that Republicans are likely to have a smaller majority next year.)

In a long and confusing post on Friday, Mr. Trump appeared to both step back from his threat to withdraw the nomination (“Todd Blanche, a good man, should be immediately approved as U.S. Attorney General”) and reiterate his support for creating the anti-weaponization fund, which could be used to compensate rioters who ransacked the Capitol on Jan. 6, 2021. Neither was helpful to Mr. Blanche.

“I will always feel that these victims of government abuse should be paid back for what they were forced to endure, their lives have been ruined!” the president wrote. “Millions of people agree with me, as was proven in my landslide Presidential win, where this was a major subject of debate, and so did John Cornyn, until he lost his Election to an opponent that I Endorsed.”

Mr. Blanche, according to current and former officials, long ago adopted a fatalistic view about Mr. Trump’s approach — and understands that coping with his demands, rages and U-turns is the price to pay for rising in his orbit.

It is nonetheless striking that Mr. Trump appeared to be willing to leave him in limbo given Mr. Blanche’s actions on his behalf, both as a defense lawyer and a government official.

Even before Pam Bondi was removed as attorney general, Mr. Blanche had been working on a spate of actions intended to demonstrate progress to Mr. Trump, including plans to move against the former C.I.A. director John O. Brennan and a former White House aide, Cassidy Hutchinson. A few weeks after Ms. Bondi was dismissed, Mr. Blanche approved the indictment of James B. Comey, the former F.B.I. director, for posting a photo of seashells arranged to read “86-47.”

Mr. Blanche has repeatedly said he did not personally negotiate the details of the deal to settle Mr. Trump’s lawsuit against the I.R.S. over the leak of his confidential tax returns to The New York Times. One of his subordinates, Trent McCotter, drafted the agreement with Mr. Trump’s private legal team, which included a longtime Trump adviser, Boris Epshteyn, who played a significant role in coordinating and holding discussions with all of the sides involved.

Mr. Blanche expressed concerns internally about the plan. But he determined that it passed muster legally and agreed to mitigate the backlash, which now threatens his nomination.