U.S. President Barack Obama's chief of staff is stepping down after only a year.

Mr. Obama announced on Tuesday that William Daley will be replaced by White House budget director, Jack Lew. The Associated Press reports the transition is expected to take place at the end of the month.

The president says Daley's resignation was not easy news to hear, but praised his “extraordinary work.”

“Bill has been an outstanding chief of staff during one of the busiest and most consequential years of my administration.”

A former businessman and commerce secretary under President Bill Clinton, Daley became Obama's chief of staff in January 2011. He replaced current Chicago mayor Rahm Emanuel.

Daley was not expected to resign until after the November presidential election, but he is believed to have had a rocky tenure with other members of Obama's inner circle.

He set the stage for his resignation by handing over the day-to-day operations of the White House to Obama aid Pete Rouse in November.

Mr. Obama said that Daley called Lew the “clear choice” for his successor. Lew is a former deputy to Secretary of State Hillary Clinton and was budget director during the Clinton administration in the 1990s.

The president said Daley will return to his hometown of Chicago to spend more time with his family.