As chief of staff and head of OMB, Lew has already been a key player in several negotiations between the White House and Capitol Hill, including the recent talks to avert the "fiscal cliff."
A fresh series of economic deadlines would await Lew at the Treasury Department. The first will be the need, around the end of February, to raise the $16.4 trillion federal borrowing limit to avert a first-ever default by the government. That deadline is likely to bring a fresh confrontation with congressional Republicans over spending cuts.
Also, at the beginning of March, $110 billion in cuts to military and domestic programs will automatically kick in if no congressional budget deal has been reached by then. Congress and the administration postponed that issue in the fiscal cliff agreement that received final congressional passage on New Year's Day.
The third pressing deadline will occur March 27. That's when a congressional resolution that's keeping the government operating without a budget will expire. Without a new bill, the government could shut down.
The leading candidates to replace Lew as White House chief of staff are Deputy National Security Adviser Denis McDonough and Ron Klain, the former chief of staff for Vice President Joe Biden.
Associated Press writer Jim Kuhnhenn contributed to this report.
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