"Secretary Powell is doing an outstanding job over at the State Department. He has helped us accomplish many great things to make the world stronger and safer, and we appreciate his service," White House spokesman Scott McClellan told a news briefing.

"He will continue to work in that capacity, I expect, until his replacement is confirmed by the Senate," McClellan said.

Powell is expected to go about his usual schedule, a senior administration said earlier. Powell was scheduled to meet later Monday with Israeli Foreign Minister Silvan Shalom and was to attend a meeting of Asian officials in Chile Wednesday and a multinational conference on Iraq next week.

McClellan declined to say if Powell's resignation is accepted by President George W. Bush, saying "Powell made a decision for his own reasons that this was now the time to leave."

McClellan also praised three other cabinet members - Agriculture Secretary Ann Venneman, Education Secretary Rod Paige and Energy Secretary Spencer Abraham - for their "service and leadership".

"The president greatly appreciates their service and leadership,and he looks forward to continuing to work with them as they work to continue their jobs until their replacements are confirmed by the Senate," the spokesman said.