While it is common for senior officials to leave office at the end of a presidential term, Secretary of State Colin Powell's resignation could seriously affect the makeup of President Bush's Cabinet.
"To my mind, the secretary of state in these times is next to the president," said Lee Strickland, director of the Center for Information Policy at the University of Maryland and former CIA senior analyst.
"He is America's ambassador to the rest of the world. ... If you look to history, those who are judged to be the best (secretaries of state are) individuals respected for their intellect."
Senior administration officials told The Associated Press that Condoleezza Rice, now national security adviser, is Bush's choice to take Powell's position.
Speculation also had centered on U.N. Ambassador John Danforth, who was considered Powell's political foil - a moderate Republican more likely to dissent on Bush's foreign policy.
Bush's choice of Rice, a longtime adviser and one of his closest confidants, demonstrates that the president likely wanted someone more in line with his policies.
"There's always speculation about the intrigue that's in the White House," said Bruce Ransom, chairman of policy studies at the Strom Thurmond Institute of Government and Public Affairs at Clemson University.
"Once a president is elected for a second term, many members of the Cabinet and high-ranking officials choose to resign."
But Ransom said comments made by White House officials Monday to CNN reporters hinted that a second term for Powell would not be compatible with future actions.