US President George W Bush has announced that national security adviser Condoleezza Rice is his choice as the new secretary of state.
Rice is part of the president's innermost circle
Ms Rice, 50, a close confidante of Mr Bush, is to succeed Colin Powell.
If confirmed in the post by the US Senate, she will be the first black female secretary of state.
Mr Bush said that during the last four years, he had appreciated the experience, counsel and "sound and steady judgement" of Ms Rice.
"The secretary of state is America's face to the world
and in Dr Rice the world will see the strength, grace and
decency of our country," Mr Bush said.
The president also announced that he would promote deputy national security adviser Stephen Hadley to succeed Ms Rice as national security adviser.
She said it was an honour to be asked again to serve her country. It was also " humbling" to succeed her mentor Colin Powell, whom she described as a "great and inspirational secretary of state."
Mr Bush also again paid tribute to Mr Powell, 67, who resigned on Monday. He said it had always been his intention to serve only one term.
His resignation was announced along with three other cabinet members, bringing to six the number of key figures to leave the 15-member cabinet.
'Driven and highly ambitious'
Ms Rice is a trusted member of President's Bush innermost circle - some describe her as almost family, the BBC's Jill McGivering in Washington says.
She is also said to share many of his views, and is described as driven and highly ambitious, our correspondent says.
Ms Rice is seen as a more abrasive character than UN ambassador John Danforth who was earlier also tipped as a possible successor to Mr Powell, analysts say.
The president's choice says much about how he intends to approach the world in his second term, which begins with his inauguration on 20 January.
Much of the foreign policy focus in the second term is likely to be firmly on the Middle East but Ms Rice's background as a Russian expert will prove useful at a time of concern about President Vladimir Putin's handling of political and civil rights.
The Bush administration seems keen to exert firm control over the state department and Ms Rice's appointment will certainly bring it strongly back into the fold, our correspondent says.
There was speculation that the only reason she might turn down the post was because she coveted the defence portfolio but that has not become vacant.