WASHINGTON - Unable to win Senate confirmation, U.N. Ambassador John Bolton will step down when his temporary appointment expires within weeks, the White House said Monday.

John Bolton appears before the Senate Foreign Relations Committee on Capitol Hill in this Monday, April 11, 2005 file photo, on his nomination to be ambassador to the United Nations. Unable to win Senate confirmation, U.N. Ambassador John Bolton will step down when his recess appointment expires soon, the White House said Monday, Dec. 4, 2006. [AP]

Bolton's nomination has languished in the Senate Foreign Relations Committee for more than a year, blocked by Democrats and several Republicans. Sen. Lincoln Chafee, a moderate Republican who lost in the midterm elections Nov. 7 that swept Democrats to power in both houses of Congress, was adamantly opposed to Bolton.

Critics have questioned Bolton's brusque style and whether he could be an effective bureaucrat who could force reform at the U.N.

President Bush gave Bolton the job temporarily in August 2005, while Congress was in recess. Under that process, the appointment expires when Congress formally adjourns, no later than early January.

The White House resubmitted Bolton's nomination last month. But with Democrats capturing control of the next Congress, his chances of winning confirmation appeared slight. The incoming chairman of the Senate Foreign Relations Committee, Democratic Sen. Joe Biden of Delaware, said he saw "no point in considering Mr. Bolton's nomination again."

While Bush could not give Bolton another recess appointment, the White House was believed to be exploring other ways of keeping him in the job, perhaps by giving him a title other than ambassador. But Bolton informed the White House he intended to leave when his current appointment expires, White House deputy press secretary Dana Perino said.

Bush planned to meet with Bolton and his wife later Monday in the Oval Office.

As late as last month, Bush, through his top aides, said he would not relent in his defense of Bolton, despite unwavering opposition from Democrats who view Bolton as too combative for international diplomacy.

Perino said that among Bolton's accomplishments, he assembled coalitions addressing North Korea's nuclear activity, Iran's uranium enrichment and reprocessing work and the horrific violence in Darfur. She said he also made reform at the United Nations a top issue because the United States is searching for a more "credible" and more "effective."

"Ambassador Bolton served his country with distinction and he achieve a great deal at the United Nations," Perino said.

"Despite the support of a strong bipartisan majority of senators, Ambassdor Bolton's confirmation was blocked by a Democratic filibuster, and this is a clear example of the breakdown in the Senate confirmation process," she said. "Nominees deserve the opportunity for a clean up or down vote. Ambassador Bolton was never given that opportunity."

Perino said Bush had reluctantly accepted Bolton's decision to leave when his current appointment expired.