Gates said the decision did not reflect on Pace's performance, but rather on the desire to avoid a "contentious" hearing before Congress, which has indicated it would want to review shortcomings of US military strategy in Iraq and Afghanistan.

"It had been my intention to recommend that General Pace be renominated for another two year term," Gates told reporters.

"I am no stranger to contentious confirmations, and I do not shrink from them," Gates said at a hastily arranged news conference.

"However, I have decided that at this moment in our history, the nation, our men and women in uniform and Gen. Pace himself would not be well served by a divisive ordeal. ..."

Gates said he also will recommend Gen. James E. Cartwright, currently the commander of the Strategic Command, as the next vice chairman of the Joint Chiefs of Staff. He would succeed Adm. Ed Giambastiani.

US President George W Bush, who was visiting Poland and Italy on Friday, praised Pace as an example for all men and women in uniform, and saluted his years of service in the military.

"President Bush appreciates Gen. Pace's long and distinguished service to the country and as chairman of the Joint Chiefs of Staff," said White House spokesman Gordon Johndroe, who was traveling overseas with Bush. "He is an example for all our men and women in uniform and has been an integral part of the president's national security team."