Secretary of Defense Chuck Hagel, the highest profile Republican on President Obama's cabinet, will step down, a defense official tells NPR's Tom Bowman.
The White House says President Obama will make a "personnel announcement" at 11:10 a.m. ET.
Hagel, a two-term Republican Senator, came to this post in February of 2013, the first enlisted combat veteran to lead the Department of Defense.
The New York Times, which first reported the story, says Obama made the decision on Friday after several meetings. The Times adds:
"The officials described Mr. Obama's decision to remove Mr. Hagel, 68, as a recognition that the threat from the Islamic State would require a different kind of skills than those that Mr. Hagel was brought on to employ. A Republican with military experience who was skeptical about the Iraq war, Mr. Hagel came in to manage the Afghanistan combat withdrawal and the shrinking Pentagon budget in the era of budget sequestration.
"But now 'the next couple of years will demand a different kind of focus,' one administration official said, speaking on the condition of anonymity. He insisted that Mr. Hagel was not fired, saying that he initiated discussions about his future two weeks ago with the president, and that the two men mutually agreed that it was time for him to leave."
The news comes just as American troops are completing their combat role in Afghanistan and just as the administration announced a new war against the Islamic State in Iraq and Syria.