William Daley resigned Monday as White House Chief of Staff to be replaced by Budget Director Jacob Lew. President Obama made the announcement during a brief appearance at the White House and said that the change will be effective at the end of January. The president said that Daley had asked to resign in order to return to his native Chicago. According to the Washington Post, a source said that Daley will serve as one of the co-chairs of President Obama's reelection campaign. Lew served as Budget Director in the Clinton Administration from 1998 to 2001 and resumed the position in November 2010. He played a critical role in the White House during debt talks with Congress last year. “Jack [Lew] is taking one of the most difficult jobs in Washington, but Jack has had one of the most difficult jobs in Washington,” President Obama said. “His economic advice was invaluable. He has my complete trust.”