By no means has Mr. Mulvaney been completely shut out: A White House official said that on Tuesday, Mr. Mulvaney participated in a meeting with the president about the debt ceiling. And two administration officials said that Mr. Trump’s lack of interest in the talks meant that the acting chief of staff could dip in and out of the discussions, sticking to the big picture without getting sucked into the minutiae.
At times, he has privately expressed bemusement at what he calls Mr. Mnuchin’s naïveté when it comes to haggling with Congress. In the spring, when Mr. Mnuchin suggested that House Democrats would be amenable to a “clean” raising of the debt ceiling — without preconditions, like raising the spending caps — Mr. Mulvaney insisted that Ms. Pelosi would surely try to extract concessions — as he would have.
He is likely to be proved right.
And Mr. Mulvaney certainly sees himself in charge. At a Heritage Foundation forum on Wednesday, Mr. Mulvaney said that he often joked that the White House budget office was now under the conservative think tank’s management.
But two administration officials acknowledged that Mr. Mulvaney’s diminished role in the budget negotiations could be in response to the bipartisan contingency on Capitol Hill that does not want him there. Mr. Mulvaney was seen poorly by those legislators, White House officials suggested, because they want to spend more than he does.
Like Ms. Pelosi, Senator Mitch McConnell, the majority leader, has also singled out Mr. Mnuchin as the preferred lead negotiator among the three administration officials — Mr. Mnuchin, Mr. Mulvaney and the acting budget director, Russell T. Vought — who have traipsed up to the Capitol in recent weeks for talks.
“By all accounts, Secretary Mnuchin is very outcome driven and that’s what this is about,” said Antonia Ferrier, a former top aide to Mr. McConnell. “He’s uniquely positioned to work this through, because he’s dispassionate, he listens, he’s respected and he’s not playing games.”
Aides to Mr. Mnuchin and Mr. Mulvaney say that the two men have a constructive working relationship, but that their backgrounds, ideologies and negotiating styles starkly differ. Stephanie Grisham, the White House press secretary, said, “The president has confidence in his team and the progress that is being made.”