The Senate on Thursday narrowly approved Mick Mulvaney to be the director of the Office of Management and Budget.
Mulvaney's rocky path to the nomination cleared a major hurdle Wednesday when Sen. Susan Collins, R-Maine, who had been withholding support for Mulvaney, announced she would approve the South Carolina Republican.
He was approved in a partisan 51 to 49 vote.
Sen. John McCain, R-Arizona, was the lone Republican to oppose Mulvaney, saying he could not back an opponent of government spending to a position that oversees implementation of the president's and Congress' budget policies and priorities.
McCain said on the Senate floor Wednesday that Mulvaney's ardent opposition to defense spending was why he couldn't support him.
Mulvaney, who was elected in the Tea Party wave of 2010, has opposed legislation that would not reduce the federal budget and or would raise the debt ceiling.
He also failed to pay taxes for three years for a caregiver for his triplets.
Mulvaney's confirmation comes the day after fast food chain chief executive Andy Puzder became the first Cabinet nominee to withdraw as his support, even among Republicans, waned.
President Donald Trump's nominees have been described as the most partisan in modern history.
Five Senate confirmation votes have proceeded mostly along party line votes, with Democrats opposing and Republicans mostly supporting. However, there have been some defectors, including two Republicans, Collins and Lisa Murkowski of Alaska, who voted against Betsy DeVos to be education secretary and Joe Manchin, D-West Virginia, who voted for Sen. Jeff Sessions to be attorney general.