Not only will President Obama likely have to adjust next year to at least a GOP-controlled House, he will have to replace several top advisers. Lawrence Summers (in photo), Obama's chief economic adviser, is returning to Harvard University. Chief of Staff Rahm Emanuel is expected to run for mayor of Chicago. And senior adviser David Axelrod likely will leave in the spring to start working on Obama's 2012 campaign. Departures aren't that unusual after two years in office — though they look bad, given Obama's slumping approval ratings. But they also are an opportunity for Obama to refocus and adjust priorities, which could make him more effective. President Clinton arguably became a more successful president after the GOP took control of Congress in 1994.