The Senate approved of President Trump's chief budget and policy aide on Thursday, in a 51-49 vote.
Sen. John McCain (R-Ariz) was the lone Republican to reject Rep. Mick Mulvaney (R-SC), on the grounds that the Tea Party Congressman has extended his frequent calls for fiscal austerity to the defense budget.
Mulvaney is now set to lead the Office of Management and Budget, an influential wonky arm of the White House through which draft "major rules" receive edits before publication.
The agency is also tasked with issuing "statements of administration policy"on legislation winding its way through Congress. The declarations are the vehicle through which the White House issues veto threats.
Mulvaney's appointment to lead the influential OMB has raised questions about some of President Trump's key campaign promises, given the congressman's well-documented opinions on the welfare state.
Though Trump repeatedly vowed not to cut Medicare or Social Security, in Mulvaney, he has appointed a budget chief who once declared the programs unconstitutional.
During his confirmation hearing, Mulvaney said that he would not be urging the President to argue that the two programs violate the constitution. He nonetheless would not back off past calls to cut benefits paid out by Medicare and Social Security.
"It seems to me that Rep. Mulvaney is way, way out of touch with what the American people want and what President Trump campaigned on," Sen. Bernie Sanders (I-Vt.) said at Mulvaney's confirmation hearing.
Sanders noted he was not only opposed to Mulvaney's appointment on ideological grounds, but that his very nomination highlighted problems with "the integrity and the honesty" of Trump.