President Obama is expected to nominate his top counterterroism adviser, John Brennan, to head the Central Intelligence Agency.
Brennan's worked for the agency 25 years, but withdrew his name from consideration for the top job in 2008 after questions about whether he supported controversial interrogation techniques under the Bush administration.
The president is also expected to nominate former Senator Chuck Hagel as Secretary of Defense.
A Purple Heart-veteran wounded in Vietnam, Hagel is a moderate Republican who criticized the Iraq troop surge, opposed unilateral sanctions against Iran, referred to pro-Israel groups as "the Jewish lobby" and once said being gay inhibits effectiveness.
"He apologized for it," President Obama said of Hagel, "and I think that anybody who serves in my administration understands my attitude and position on those issues."
Republicans call him a controversial "in your face" pick.
If confirmed, Hagel would oversee the wind-down of troops in Afghanistan, a war he supported, then criticized.
Republicans are planning to throw him tough questions, but pledging to be fair stopped short of saying they'd block his nomination.