US President George W. Bush on Tuesday nominated national security adviser Condoleezza Rice to replace Colin Powell as secretary of state in Bush's second term.

"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,'' Bush said of his national security adviser.

In her speech at the nomination ceremony at the White House, Rice said to Bush that "Under your leadership, America is fighting and winning the war on terror."

The nomination of Rice should be confirmed by the Senate. If confirmed, Rice would be the first black woman secretary of state in American history.

In the nomination ceremony, Bush also thanked Powell, a former chairman of the Joint Chiefs of Staff and national security adviser, for working "tirelessly and selflessly'' on behalf of the country.

Bush named Stephen Hadley, Rice's deputy, to replace her as national security adviser, the top White House-based foreign policy adviser.