Bill Cassidy, the US Republican senator seen as the decisive holdout on Todd Blanche’s nomination for attorney general, announced on Friday that he will support the pick, setting the stage for a major win for Donald Trump.

Confirmation that Cassidy, of Louisiana, is prepared to back Blanche – Trump’s former personal lawyer, and a loyal ally of the president – appeared to clear the last hurdle of his confirmation process, which had been challenged by the defections of the Republican senators Lisa Murkowski and Susan Collins.

Blanche is already serving as acting attorney general.

“I will vote for Mr Blanche,” Cassidy said in a US Senate floor speech on Friday morning. “Mr Blanche is not perfect, and he will tell you this, but the choice is not between perfection and Mr Blanche; it is between Mr Blanche and another acting attorney general who may not run the department effectively under President Trump, and who indeed may not be as good as Mr Blanche.”

With Cassidy now on board, Blanche is expected to be confirmed by a narrow margin, probably along party lines, as the Senate works through a final vote series before senators leave for the five-week August recess that starts this weekend.

Cassidy, who lost his Louisiana primary in May after facing two challengers, including one backed by Trump, had faced weeks of pressure from the White House and had voiced concerns about “lawfare” at the justice department before announcing his decision.

Murkowski, Alaska’s moderate Republican senator, had announced earlier on Friday that she would not vote for Blanche’s confirmation, leaving his path to the job down to a single Republican vote.

Murkowski’s announcement came a day after Trump, speaking to reporters in the Oval Office on Thursday, was asked about his fraying relationships with Republican critics including Murkowski and Cassidy and whether the president would reach out to either Republican senator to save the vote.

“I’ll reach out to whoever I have to, but anybody voting against [Blanche] would be doing a great disservice to the country,” Trump told reporters.

“People have such unbelievable respect” for Blanche, he claimed, expressing hope that reaching out to those lawmakers “won’t be necessary”.

Maine’s Susan Collins had already said she will oppose Blanche’s confirmation over concerns about the independence of the US Department of Justice, and with Murkowski’s opposition now confirmed, Cassidy had been the last undecided Republican vote standing between Blanche and confirmation.

Murkowski and Cassidy were among the handful of Republicans who voted to convict Trump after his 2021 impeachment over the January 6 Capitol riot. After the Oval Office meeting, Trump acknowledged the political toll his feuds with GOP holdouts have taken.

“Look, I don’t regret it. You do what you have to do,” Trump told Punchbowl News. “And just so you understand, they voted to impeach me … In all fairness, you think that I’m going to support somebody that voted to impeach me?”

She took her stance even though Blanche confirmed in writing the controversial fund was dead. Experts say Trump could easily reverse it. Murkowski said the Senate only currently has leverage over the fund because Blanche’s nomination to head the Department of Justice is pending necessary confirmation by the upper congressional chamber.

Blanche had persuaded the Senate judiciary committee in a 12-10 vote in his favor earlier this week only because he promised Republican holdouts that he would not pursue the payout fund.

Blanche issued a formal order late on Sunday terminating Trump’s $1.8bn “anti-weaponization” slush fund designed to compensate political allies who had been “targeted” by the justice department, including prosecutions of January 6 insurrectionists. That move followed weeks of negotiations with two Republican senators who were blocking his nomination to become attorney general – Thom Tillis and John Cornyn, who were eventually swayed by Blanche.

Murkowski posted on X on Friday, praising Blanche but then saying “ultimately” she would oppose his nomination, a position she took on Tuesday and is now sticking with.

“The country needs an Attorney General who will check the worst impulses of this administration. I hope Mr Blanche is able to achieve that, if confirmed, but I simply do not have confidence that will be the case,” she wrote, as part of a much longer post on the topic.

Republicans hold a 53-47 Senate majority, but Mitch McConnell of Kentucky, who was just released from the hospital, is not attending sessions because of his health.