The Senate Foreign Relations Committee agreed Friday to vote on May 12 on John R. Bolton's (search) nomination as U.N. ambassador, and the White House renewed its support for the troubled nominee.

The GOP-led committee will examine roughly a dozen allegations of abusive or high-handed behavior by Bolton, with an agreement to complete that work by May 6, said Andy Fisher, a spokesman for the committee's Republican chairman, Sen. Richard Lugar of Indiana. There are no plans to ask Bolton to return for more questions.

Lugar was forced to postpone a vote scheduled for last Tuesday when it became clear that he had lost a crucial GOP vote.

The White House (search) is pressing ahead with the nomination despite cracks in Republican support for Bolton.

"If being occasionally tough and aggressive and abrasive were a problem, a lot of members of the U.S. Senate wouldn't qualify," Vice President Dick Cheney (search) said Friday.

His audience at the Republican National Lawyers' Association (search) laughed and Cheney added, "They're all friends of mine."

Meanwhile, President Bush's former ambassador to South Korea is challenging Bolton's Senate testimony and his diplomatic style.

The criticism leveled at the nominee for U.S. ambassador to the United Nations by retired career diplomat Thomas Hubbard (search), who held the Seoul post during Bush's first term, adds to allegations by several former and current State Department officials that Bolton mistreated them and threatened their careers.

Bolton has denied the charges in sworn testimony to the committee, and the Bush administration is portraying Democratic efforts to derail Bolton's troubled nomination as a smear campaign.

On Friday, a White House spokesman declined to talk about discussions former Secretary of State Colin Powell (search) has had with some senators about Bolton.

Asked about Powell's involvement, White House press secretary Scott McClellan would say only, "The Senate needs to put aside politics and get him confirmed."

Powell has talked to several senators at their request about specific questions that had been raised about Bolton, his spokeswoman Peggy Cifrino said Thursday.

"The general considers the discussions private," Cifrino said.

Among the senators Powell called was Lincoln Chafee, R-R.I., who last week said he was inclined to vote for confirmation but this week said the "dynamic" had changed.

Powell was the only former Republican secretary of state who did not sign a letter of support for Bolton that was sent to Lugar.

Their views often were at odds, with Powell generally taking a moderate position on world issues while Bolton, like Bush, hewed to a hard line.

The president showed no sign of wavering. "John's distinguished career and service to our nation demonstrates that he is the right man at the right time for this important assignment," Bush said.

Dan Bartlett, the president's counselor, vowed to "do everything we can to get him confirmed."

"We believe that there are very reasonable answers to the accusations that are being leveled, and they have been shared with the committee," Bartlett said.

Reflecting slipping Republican support -- three Republicans on the committee appear to be fence-sitters -- Majority Leader Bill Frist said he strongly supports Bolton but admitted "I can't speak for all of leadership" of the Senate GOP.

As it resumed digging into Bolton's past, the Foreign Relations panel received accusations of confrontation and undiplomatic behavior from Hubbard, who retired from the foreign service last year and joined a Washington law firm.

Hubbard told a reporter that Bolton berated him for failing two years ago to arrange a meeting with the president-elect of South Korea, Roh Moo-Hyun.

"He hung up on me," Hubbard said. "He was very angry."

Also, Hubbard said, Bolton refused to attend a dinner the ambassador had arranged with senior South Koreans. "It was undiplomatic behavior," he said.

Hubbard challenged Bolton's testimony to the committee that he had praised Bolton for a speech that year denouncing Kim Jong Il, the leader of North Korea, as a "tyrannical dictator."

Hubbard said he had advised Bolton against making the speech, which prompted North Korea to denounce Bolton as a "bloodsucker" and complicated already difficult negotiations on Pyongyang's nuclear weapons program.

"I asked Bolton to tone the speech down," Hubbard said. The undersecretary of state, who is the senior international security official in the State Department, agreed to make some changes but went ahead with his denunciation of the "Dear Leader," Hubbard said.

Even so, Hubbard said he had not taken a position on Bolton's nomination, nor joined more than 60 retired U.S. diplomats in a letter to Lugar opposing Bolton's confirmation.