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.”
At times they have knocked heads: Last year, Mr. Mnuchin and Mr. Mulvaney clashed over who would have the final say about rules for enforcing the Republican tax overhaul passed in 2017. Mr. Mulvaney, then the head of the budget office, succeeded in wresting control over how to interpret tax regulations from the Treasury Department over Mr. Mnuchin’s objections.
When Mr. Trump needed to replace his chief of staff in late 2018, some of Mr. Mnuchin’s aides privately expressed dismay that Mr. Mulvaney was tapped for the job.
Aides to both men have said that their differences were largely institutional rather than personal. John Czwartacki, a spokesman for Mr. Mulvaney, said that despite the fact that his style differed from Mr. Mnuchin, Mr. Mulvaney was ultimately looking for an outcome that would be good for the economy.
“Good cop, bad cop, he’s happy to play any role that gets the best deal for the hard-working American taxpayer,” Mr. Czwartacki said.