(Updates with Bush comments in Fox interview) By Steve Holland WASHINGTON, Dec 4 (Reuters) - U.S. Ambassador to the United Nations John Bolton announced on Monday he will step down and give up his bruising fight to convince enough Senate opponents to back him for a post they said he was ill-suited to fill. President George W. Bush said he accepted Bolton's resignation reluctantly. "I'm not happy about it," he told reporters in an Oval Office meeting with the mustachioed Bolton and his wife, Gretchen. Bolton had a history of angering diplomats and colleagues in his previous State Department job. Bush bypassed the Senate and appointed Bolton to the U.N. job on a temporary basis in August 2005 despite protests that he would pursue a unilateral foreign policy. When Bolton turned out to be far less of a lightning rod than expected, Bush tried again to gain Senate confirmation for him, but the opposition largely remained and the Democratic takeover of the Senate in November elections made the path even more difficult. Bush blamed "shallow politics of the Senate" and said Bolton had done a fine job despite his critics. "He proved the critics wrong, I mean flat wrong," Bush told the Fox News Channel in an interview. "They weren't even close as they characterized John Bolton, as they anticipated his office, what he would do in office." His departure gives Bush the opportunity to fill the key diplomatic position with a less ideological choice, much like the president is doing with Robert Gates as the nominee to replace Donald Rumsfeld as defense secretary. While there was much speculation in Washington that Bush might give Bolton another position that did not require Senate confirmation, Bolton's departure letter appeared to close the door on that option. He is to leave the U.N. post when the current session of the U.S. Congress ends, possibly at the end of the week. Democrats take control of both the Senate and the House of Representatives when the new session begins in January. "After careful consideration I have concluded that my service in your administration should end when the current recess appointment expires," Bolton wrote. BULL LEAVING THE CHINA SHOP Surprising some White House officials still searching for a way to keep him in his job, Bolton submitted a resignation letter to Bush on Friday. Aides said Bush thought about it over the weekend before accepting it. White House spokesman Tony Snow said Bolton's departure "will disrupt our diplomacy at the United Nations, to a certain extent, until we find somebody in his stead." He had no word on when a new nominee might come. Bolton is leaving at a time when U.S. foreign policy is fraught with global challenges, from the Iraq war to the nuclear ambitions of North Korea and Iran. "The bull is leaving the china shop of multilateral politics. This is good news for the world -- and the U.S.A.," said Juergen Trittin, former environment minister and deputy head of the opposition Greens in the German parliament. Nicholas Burns, the undersecretary of state for political affairs, was considered a possible replacement, as was the U.S. ambassador to Iraq, Zalmay Khalilzad. Another possibility, Iowa Republican Rep. Jim Leach, who lost his re-election bid, said last week his opposition to the Iraq war made him an unlikely choice. Democrats were largely opposed to Bolton. But a key Republican opponent was Rhode Island Sen. Lincoln Chafee, who lost his re-election bid even while maintaining his distance from the White House by opposing Bolton. "I have long believed that the go-it-alone philosophy that has driven this administration's approach to international relations has damaged our leadership position in the world," Chafee said in a statement. Alejandro Wolff, the deputy U.S. representative to the United Nations, is expected to be acting U.S. ambassador to the U.N. until a successor is confirmed. (Additional reporting by Susan Cornwell, Evelyn Leopold, Arshad Mohammed and Louis Charbonneau)
