WASHINGTON (AP) — President Barack Obama will nominate White House chief of staff Jack Lew to be his second-term Secretary of the Treasury, turning to one of Washington's most knowledgeable budget experts to manage prickly fiscal negotiations with Congress and steer the still-shaky national economy. Lew's nomination, expected Thursday, accelerates the overhaul of Obama's top advisers, with new leaders at the Pentagon, State Department, Central Intelligence Agency and Labor Department. Obama also must replace Lew with a new chief of staff, and that could have a ripple effect through the West Wing's senior ranks.