Senator Max Baucus of Montana, the Democrat who chairs the Finance Committee, had wondered if Lew had sufficient gravitas to be the chief U.S. economic spokesman during a committee hearing this month.
But he later endorsed Lew for the post, commending his commitment to bipartisanship.
"If confirmed, we'll be entrusting Mr. Lew to oversee America's economic policy," Baucus said before the Senate vote. "It is a great responsibility, one I believe Mr. Lew will live up to."
Lawmakers in both parties praised Lew when he said revamping the byzantine U.S. tax code would be a top priority. But prospects for achieving tax reform are clouded by Washington's constant fiscal fights.
The new secretary also will also have to deal with the growing clout of China.
He has pledged to press the world's second-largest economy to further loosen its currency restrictions. Lawmakers have complained China keeps the value of the yuan artificially low to boost its exports, hurting American manufacturers.
Other delicate tasks for Lew include implementing new financial regulations and finding a way to wind down government-controlled mortgage finance giants Fannie Mae and Freddie Mac, which have drawn almost $190 billion from the Treasury.
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