White House Chief of Staff Bill Daley steps down
White House Chief of Staff Bill Daley is stepping down, US President Barack Obama has said.
The president named Budget Director Jack Lew, a Washington veteran, as his replacement.
Mr Daley joined the White House staff in January 2011 to succeed Rahm Emanuel, who stepped aside as chief of staff to become mayor of Chicago.
Mr Daley, a former vice-chairman at JP Morgan Chase, had said he would work with the president until the elections.
President Obama said Mr Daley had decided to leave his post at the White House in order to return to his hometown of Chicago and spend more time with his family.
"In the end the pull of the hometown we both love... was too great," he said, adding that the former banking executive had been an "outstanding" chief of staff.
The president also said Mr Daley's resignation "was not easy news to hear" and that he had not accepted the decision immediately.
"No-one in my administration has had to make more important decisions more quickly than Bill, and that's why I think this decision is difficult for me," Mr Obama said.
The announcement came hours after White House spokesman Jay Carney downplayed claims in a new book of tensions between Michelle Obama and key presidential staff as "over-hyped".
President Obama announced the appointment of Mr Lew at the same time, saying that the new chief of staff would ensure he "won't miss a beat".
The two men - Mr Daley and Mr Lew - flanked the president as he made the announcement.
The White House chief of staff role controls access to the president, handling crises and acting as both enforcer and liaison to a sometimes hostile Congress.
Mr Daley's father, like his brother Richard, was a dominant Chicago figure, serving as the city's mayor for more than two decades.
Mr Daley was brought in after the 2010 mid-term elections to rebuild relations with the business community, according to White House insiders.
But it has been reported that Mr Daley did not integrate well with the president's inner circle of political advisers.
The president's liberal base, especially Congressional Democrats, accused him of lumping them together with the Republican opposition.
Mr Daley was credited with helping to pass the summer's debt ceiling deal, but was also blamed for failing to settle deficit talks with Congressional Republicans.
In November, day-to day management responsibilities of the office were handed over to Pete Rouse, who had served as the interim White House chief of staff after the departure of Rahm Emanuel.
One analyst suggested that the timing of the announcement benefited Mr Obama.
"This is a good time for a shake-up," Julian Zelizer, a Princeton University history professor, told Reuters news agency.
"Since public attention is focused on the GOP, thereby diminishing the chances this will become a story about unrest in the White House."
Mr Lew is currently the director of the Office of Management and Budget, a position he also occupied under former President Bill Clinton. He has been a leading figure in Democratic fiscal policy since the 1980s.
He has been described as a "grey technocrat" and a "translator" - a man who is able to work with politicians on both sides of the aisle.
Mr Lew will officially take up his new role at the beginning of February, after work on the president's budget is complete.