U.S. Ambassador to the U.N. John Bolton officially abandoned his quest to remain at the world body next year, sending formal notice to the White House that he will leave when his temporary appointment expires in the coming weeks.

The White House, which had been holding out hope for Bolton despite the writing on the wall, has been tight-lipped about any other possible candidates for the U.N. post. Deputy Amb. Alejandro Wolff is expected to fill in as acting ambassador until a nominee can be confirmed by the new Democratic-controlled Senate in January, at the earliest.

At least one Democrat, Sen. Bill Nelson of Florida, threw in a familiar name to the Bush administration as a possible nominee.

"I would suggest (President Bush) consider Undersecretary of State for Political Affairs Nicholas Burns," Nelson told FOX News.

"There are many qualified candidates from across the political spectrum with the respect and experience necessary to be effective in this crucial post," added Sen. John Kerry, D-Mass.He said a new nominee must be confirmed "with broad bipartisan support."

Bush is scheduled to meet with Bolton and his wife in the Oval Office later in the day Monday. It's unlikely he would suggest any replacements.at that event.

"It is with deep regret that I accept John Bolton's decision to end his service in the administration as Permanent Representative of the United States to the United Nations when his commission expires," the president said in a statement Monday after the White House announced Bolton's expected departure. White House spokeswoman Dana Perino said Bush reluctantly accepted Bolton's decision to leave.

"I am deeply disappointed that a handful of United States senators prevented Ambassador Bolton from receiving the up-or-down vote he deserved in the Senate. They chose to obstruct his confirmation, even though he enjoys majority support in the Senate, and even though their tactics will disrupt our diplomatic work at a sensitive and important time. This stubborn obstructionism ill-serves our country and discourages men and women of talent from serving their nation," the president said.

Bolton sent his departure letter to the White House on Friday.

"After careful consideration, I have concluded that my service in your administration should end when the current recess appoint expires," he wrote.

Click here to read Ambassador Bolton's letter to President Bush (pdf).

The Bush administration had been searching for some way to keep him in the post of chief U.S. diplomat but had given up on getting any sort of straight-up confirmation after Bolton had been unable to win support from Democrats on the Senate Foreign Relations Committee as well as at least one Republican, Sen. Lincoln Chafee, who lost in the midterm election Nov. 7.

Administration officials had thought Bolton could get confirmed if his nomination could get to the floor, but going around the committee process would have created too much collateral political damage in the new Congress and was ruled out.

"You know, 58 senators have been on record as being for this guy and he can't get a vote. He has been incredibly successful as our U.N. ambassador, he has a record that everybody ought to be proud of, and instead he can't get a vote. And that is just ridiculous," White House Press Secretary Tony Snow told FOX News Talk's "Brian and the Judge" show.

With Democrats taking over the majority in both chambers of Congress, Republicans returning for a lame duck session this month said they had other issues they needed to tackle before the 109th Congress adjourned.

Officials had considered appointing Bolton to another high-level position, including the post recently vacated by Philip Zelikow, who served as counselor to Secretary of State Condoleezza Rice. The thinking was he could then be named acting ambassador to the U.N., but that too was ruled out.

Bolton got a recess appointment in August 2005 after being denied a vote for months after his confirmation hearing. Critics said Bolton's brusque style had turned them off, and they questioned whether he could be an effective bureaucrat who could force reform at the U.N.

A recess appointment expires when Congress formally adjourns, no later than early January. A second recess appointment is not permitted. The White House resubmitted Bolton's nomination last month, but incoming chairman of the Senate Foreign Relations Committee, Sen. Joe Biden of Delaware, said he saw "no point in considering Mr. Bolton's nomination again."

Biden said Monday that the White House is falsely claiming that Bolton's nomination was blocked by Senate Democrats. "In fact, Mr. Bolton did not have the votes to secure the recommendation of the Foreign Relations Committee under Republican leadership," Biden said.

White House spokeswoman 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 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" U.N.

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

Secretary-General Kofi Annan, who steps down as U.N. chief on Dec. 31, said he thought "Ambassador Bolton did the job he was expected to do."

"He came at a time when we had lots of tough issues from reform to issues on Iran and North Korea. I think as a representative of the U.S, government, he pressed ahead with the instructions he had been given and tried to work as effectively as he could," said Annan.

Bolton supporters, even some late to the game, also expressed disappointment. Sen. George Voinovich, R-Ohio, a member of the Senate Foreign Relations Committee, had objected to Bolton when he was up for consideration in the Senate panel. But after Bolton served for a year in the recess appointment, Voinovich said he was impressed by how effective Bolton had been.

"I am very disappointed that John Bolton will not continue in his role as ambassador to the United Nations," Voinovich said Monday. "Given the fragile nature of the world situation and the critical task of reforming the U.N., he should have been given an up-or-down vote on the Senate floor.

"I'm extremely concerned with him leaving since he's been so deeply involved with the situations in Iran, Syria, Lebanon and North Korea and has been working in concert with fellow ambassadors toward true U.N. reform," Voinovich said.

Other Republicans, including Arizona Sen. John McCain, said Bolton's departure is a loss for the United States and a terrible commentary about the state of politics in Washington.

Bolton's "resignation today is less a commentary on Mr. Bolton than on the state of affairs in the U.S. Senate. For over a year, Democrats blocked his nomination in the Foreign Relations Committee, preventing an up or down vote on the Senate floor. In so doing, they have deprived America of the right man at the right time at the U.N.," McCain said.

But Kerry said the ambassador's departure is another opportunity to clean house.

"Like Secretary Rumsfeld's departure, Ambassador Bolton's resignation offers a chance to turn the page at a critical period. With the Middle East on the verge of chaos and the nuclear threats from Iran and North Korea increasing, we need a United Nations ambassador who has the full support of Congress and can help rally the international community to tackle the serious threats we face," he said.

FOX News' Jim Angle and The Associated press contributed to this report.