US President-elect Donald Trump has chosen US Representative Mick Mulvaney of South Carolina to be his White House budget director, turning to a fiscal conservative to help pursue his policy agenda.
The nomination to be director of the White House Office of Budget and Management will require Senate confirmation.
The announcement was made as Trump, who takes office on January 20, began his holiday vacation at Mar-a-Lago, his oceanfront club in nearby Palm Beach, Florida.
Mulvaney, 49, was an outspoken critic of former House of Representatives Speaker John Boehner, who resigned in 2015 amid opposition from fellow Republicans who were members of the House Freedom Caucus.
Mulvaney's selection points to a strategy by Trump to cut government where he can.
The president-elect in recent days has, for example, railed against what he has labelled a far too expensive new version of the Air Force One aircraft he will fly that Boeing is supposed to build.
In a statement announcing his selection, Trump called Mulvaney a strong voice in Congress for "reining in out-of-control spending, fighting government waste and enacting tax policies that will allow working Americans to thrive."
"With Mick at the head of OMB, my administration is going to make smart choices about America's budget, bring new accountability to our federal government, and renew the American taxpayer's trust in how their money is spent," Trump said.
Mulvaney said the Trump administration "will restore budgetary and fiscal sanity back in Washington".
Trump on Friday night vowed to seek approval from Congress to spend $US1 trillion ($A1.4 trillion) in new spending to rebuild America's crumbling network of roads, bridges, airports and other infrastructure as a way to create jobs and make some needed repairs.
"We are going to fix our country. It's time. We have no choice. It's time," Trump said in Orlando, Florida.
Democratic President Barack Obama had sought infrastructure spending but was thwarted by Republicans in Congress.
