Todd Blanche, whose role in a much-criticized deal to resolve President Trump’s lawsuit against the I.R.S. nearly scuttled his confirmation as attorney general, cleared a crucial hurdle on Tuesday after the Senate Judiciary Committee narrowly approved his nomination.

After a week of uncertainty, Mr. Blanche was confirmed by a 12-to-10 vote along party lines, exemplifying a widening schism over the direction of a department at the center of Mr. Trump’s effort to punish and humiliate his perceived enemies.

Mr. Blanche, the president’s former defense lawyer and the acting attorney general, broke an impasse over his confirmation after he reached an agreement with two Republican holdouts on the committee late Sunday. Mr. Blanche released written assurances that he would kill a proposed $1.8 billion compensation fund that could have been used to pay Jan. 6 rioters and limit the scope of a deal granting broad tax immunity to Mr. Trump and his family.

Mr. Blanche’s nomination now advances to the Senate floor, with a vote possible as early as this week. It was not immediately clear whether he would be confirmed, given that several Republicans have yet to commit to supporting him and that he can afford to lose only two senators on a party-line vote because of Senator Mitch McConnell’s continued absence.

Two lame-duck Republicans, Senator John Cornyn of Texas and Senator Thom Tillis of North Carolina, voted with their party’s majority on the committee after briefly defying the White House over concerns about the highly unusual fund and a tax immunity deal that could save the president $100 million.

Former department officials have said that Mr. Blanche’s written assurances can be easily reversed, or evaded. The department has broad authority to dispense cash to Mr. Trump’s allies through existing department processes. Tax experts said that the new limits on his immunity agreement did nothing to keep Mr. Trump and his family from an enormous windfall offered to no other taxpayers.

Mr. Cornyn acknowledged on Tuesday that the concessions offered in exchange for his vote could be reversed by Mr. Trump but said he hoped that Mr. Blanche would hold the line. He called Mr. Blanche a “stabilizing force” in the department who had earned enough trust with the president to tell him “hard truths,” even if he was ignored.

He concluded with a plea, asking Mr. Blanche “not to be afraid to capitalize on that earned trust when necessary for the good of the country.”

The committee vote represents a de facto endorsement by Senate Republicans of Mr. Blanche’s actions in running the day-to-day operations of a Justice Department that has surrendered much of its independence to the White House on his watch.

Republicans like Mr. Cornyn have been willing to put aside their deep concerns about Mr. Blanche’s lack of independence for the sake of partisan comity. They also see him as the best choice they could possibly get from a White House whose first pick, in November 2024, was Matt Gaetz, the former Florida congressman who had once been accused of sex trafficking.

Incensed Democrats, speaking before the vote took place, said that committee Republicans had frittered away their one chance to reassert independence and rule of law at the department — and constrained their objections to narrow questions while ignoring whether Mr. Blanche was fit to serve.

“Instead of serving the American people and upholding the rule of law and the Constitution, Mr. Blanche has aided and abetted the most corrupt administration in the history of the United States,” said Senator Richard J. Durbin of Illinois, the top Democrat on the committee.

Mr. Durbin accused Mr. Blanche of perjuring himself by denying during his confirmation hearing that he had told Mr. Durbin and his staff that creating the fund was a “mistake” during a private meeting.

“What’s left of this committee?” asked Senator Sheldon Whitehouse, a Rhode Island Democrat.

Mr. Tillis raised a new issue as he explained Mr. Blanche’s vote — the department’s sign-off on the indictment of James B. Comey, the former F.B.I. director, on widely ridiculed charges that a photograph Mr. Comey posted of seashells on a beach arrayed with a message threatened Mr. Trump.

“What I hope I see out of him is a bending of the curve of this absurdity,” he said.

He went on to accuse Democrats, under President Joseph R. Biden Jr., of initiating politically motivated investigations but conceded that the weaponization of the department was “a little bit more intense in this administration than the last one.”

For the first time, Senator Charles E. Grassley, the chairman of the Judiciary Committee, publicly endorsed the push by Mr. Cornyn and Mr. Tillis, saying he believed that it was “a crime” that it took so long for the White House and Justice Department to put the changes in writing.

Mr. Grassley, a reliable wingman for the White House, had not expressed any of those concerns previously. But on Tuesday, he said skepticism about the deal was “shared by many, including this senator,” and thanked Mr. Blanche and the White House for putting “this issue to bed once and for all.”

Mr. Blanche, who has maintained that Mr. Trump has a nearly unfettered right to dictate prosecutorial, personnel and policy decisions under Article II of the Constitution, has overseen a wholesale transformation of the department.

He has supervised the dismissals or forced transfers of experienced career lawyers, the abandonment of investigations into Mr. Trump’s political allies and a nearly nonstop succession of actions against his enemies, including the recent indictment of Mr. Comey.

Democrats said that the frenetic final negotiations that led to Mr. Blanche’s victory in the committee — including Mr. Trump’s threat to temporarily withdraw Mr. Blanche’s nomination rather than give up the fund or surrender his tax benefit — proved that he was unwilling to stand up to the president.

Hours after the committee vote, Senator Susan Collins, Republican of Maine, voiced skepticism about Mr. Blanche, saying she did not intend to back him when his confirmation reached the Senate floor.

Ms. Collins, who is running for re-election in a state that Republicans lost in 2024, said in a statement that he had “taken several actions that have further eroded” the Justice Department’s independence. She cited the settlement that Mr. Blanche negotiated in Mr. Trump’s lawsuit against the I.R.S., including his approval of the so-called weaponization fund.

Two other Republican senators have expressed concerns about Mr. Blanche’s nomination and have not committed to supporting him.

Senator Lisa Murkowski of Alaska told reporters this week that she wanted to have further conversations with Mr. Blanche. Senator Bill Cassidy of Louisiana, who lost his re-election bid to a primary challenger backed by Mr. Trump, has said he is concerned that the Justice Department may be targeting the president’s political opponents.

Mr. Cassidy has pointed in recent days to an investigation of Cassidy Hutchinson, a former White House aide who testified before Congress about the attack at the Capitol on Jan. 6, 2021.