WASHINGTON —  White House officials said Monday they expect President Bush to name Condoleezza Rice (search) to replace Colin Powell as secretary of state, sources told FOX News on Monday night.

If nominated and confirmed, Rice would be the second woman and the second African American to be the nation's top foreign policy representative.

Deputy National Security Adviser Stephen Hadley (search) will take Rice's place as head of the NSA upon her confirmation as secretary of state, FOX News has learned.

Powell sent his letter of resignation to Bush on Friday but the news of his departure was not released until Monday. Powell thanked Bush on Monday for bringing him into his first-term administration, but said the two had discussed it, and it's time for Powell to go.

"It has been my great honor and privilege to have been once again given the opportunity to serve my nation, and I will always treasure the four years that I've spent with President Bush and with the wonderful men and women of the Department of State," Powell told reporters Monday afternoon after the White House announced his decision to step down.

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"It has always been my intention that I would serve one term. And after we had had a chance to have good and fulsome discussions on it, we came to mutual agreement that it would be appropriate for me to leave at this time," Powell said.

Bush accepted Powell's resignation, as well as those of three other Cabinet secretaries, the White House announced Monday. Education Secretary Rod Paige (search), Energy Secretary Spencer Abraham (search) and Agriculture Secretary Ann Veneman (search) are all returning to private life. White House spokesman Scott McClellan said no successors would be named on Monday.

"These are all very distinguished individuals who have served their nation with honor and distinction. They all have been valuable members of the president's team and all have played a vital role in helping the president implement his agenda," White House spokesman Scott McClellan said Monday.

"I think you saw from Secretary Powell's letter that this is a discussion that they've had for some months now -- or over recent months, at least. And Secretary Powell made a decision, for his own reasons, that this was now the time to leave," McClellan said.

Commerce Secretary Donald Evans (search) and Attorney General John Ashcroft (search) have already announced their departures. Last week, Bush nominated White House counsel Alberto Gonzales (search) to replace Ashcroft.

Bush issued written statements praising the four who announced their departures Monday, but saved the most noteworthy remarks for Powell.

"Colin Powell is one of the great public servants of our time. He is a soldier, a diplomat, a civic leader, a statesman, and a great patriot. I value his friendship. He will be missed," the statement reads.

Earlier Monday, speculation on who would replace Powell centered on Rice, Deputy Secretary of State Richard Armitage (search), Deputy Secretary of Defense Paul Wolfowitz (search) and newly-named U.S. ambassador to the United Nations John Danforth (search).

FOX News' Jim Angle, James Rosen and Tony Delancey contributed to this report.