Daley, who became chief of staff one year ago, is to be replaced by Budget Director Jack Lew. President Obama is expected to make the news official later this afternoon.

White House Chief of Staff William Daley. Win McNamee | Getty Images

White House Chief of Staff William Daley is stepping down from his post and will be replaced by Budget Director Jack Lew, NPR's Scott Horsley has confirmed.

The news, first reported by the Los Angeles Times and quickly followed by other news outlets, puts "a veteran staffer of the White House, Capitol Hill and State Department in a critical position at a difficult time for the president" — a reelection year — as the Times says.

Daley became chief of staff one year ago, succeeding Rahm Emanuel (who went on to become mayor of Chicago). Last November, some of Daley's duties were shifted to deputy Pete Rouse.

Daley reportedly submitted his resignation last week.

President Obama is scheduled to make a statement at 3 p.m. ET, and its expected he'll announce the news then. We'll have more as the story develops. [Copyright 2012 National Public Radio]