President-elect Barack Obama's transition team has asked U.S. Treasury Department official Stuart Levey to temporarily serve as treasury secretary after the incoming president's nominee for the post faced questions about his tax returns that forced his confirmation hearing to be delayed. Levey has agreed to serve as treasury secretary until nominee Timothy Geithner is confirmed. Geithner nomination came under scrutiny after it was revealed that he failed to pay some back taxes and employed a housekeeper whose immigration status lapsed while she worked for him. The subsequent controversy has forced the Senate Finance Committee to postpone until next Wednesday its nomination hearing. Obama and most lawmakers appear confident that Geithner will eventually be confirmed, but the hearing delay means he will not be able to assume the post before Obama take office on January 20. Levey, Treasury's current under secretary for terrorism and financial intelligence, will act as treasury secretary pending Geithner's approval, Obama's transition team said.