The United States Senate has confirmed President Barack Obama's choice of Treasury Secretary, despite controversy over his personal taxes.
Timothy Geithner was approved by 60 votes to 34.
He will spearhead Mr Obama's response to the financial crisis and oversee the proposed bailout plan.
Speaking after being sworn in, Mr Geithner vowed to act quickly to protect the US economy from the worst financial crisis since the Great Depression.
"We are at a moment of maximum challenge for our economy and our country," he said.
Tax errors 'careless'
Faced with such a crisis, senators largely set aside misgivings about Mr Geithner's failure to pay some taxes earlier this decade. His experience in battling the financial storm as head of the New York Federal Reserve Bank, a post he relinquished on Monday, appears to have swung the vote his way.
"I would rather have a battle-hardened veteran at the helm who knows the shoals and whirlpools than a neophyte who has to wade into these churning waters for the first time," Republican Senator Orrin Hatch of Utah said in explaining his support.
Mr Geithner will immediately start work on a massive overhaul of the $700 billion US rescue programme. Within the next two weeks, he's expected to propose new efforts to unclogged frozen credit markets.
"Tim's work and the work of the entire Treasury Department must begin at once," President Obama said as Mr Geithner was sworn in. "We cannot lose a single day, because every day the economic picture is darkening, here and across the globe."
Mr Geithner's route to Treasury Secretary initially appeared plain sailing until revelations earlier this month that he had underpaid taxes for several years. He apologised for the errors, calling them "careless".