Democrats on Thursday said they still consider John Bolton too brash and ineffective to be confirmed as U.N. ambassador while Republicans maintained his year in the post proves he is right for the job.

The sharp division all but guaranteed lawmakers were headed toward another partisan showdown on the Senate floor.

"The sole thing that remains is the constitutional authority of the Senate to give its advice and consent," said Sen. John W. Warner, R-Va., arguing for Bolton's confirmation.

Bush temporarily installed Bolton as U.N. ambassador on Aug. 1 of last year while Congress was in recess, an appointment that will expire in January. The recess appointment, provided for by the Constitution, came after Democrats blocked repeated attempts by GOP leaders to grant Bolton Senate approval.

The Senate Foreign Relations Committee confirmation hearing for Bolton on Thursday twice was interrupted by protesters opposing his confirmation.

"My concern is that at the moment of the greatest need for diplomacy in our recent history, we are not particularly effective at it," said Sen. Joseph Biden of Delaware, the Foreign Relations Committee's top Democrat.

Biden and other Democrats contend Bolton should not get a confirmation vote until the White House turns over documents requested when Bolton was nominated last year.

Sen. Christopher Dodd, D-Conn., cited recent press reports on Bolton's interactions with other U.N. officials as evidence that Bolton "clearly has an aversion, in my view, to building consensus."

Shrugging off the criticism of Bolton, Republicans predicted that the U.N. ambassador would be confirmed soon for the position on a permanent basis. The White House on Thursday praised the work Bolton has done so far.

"We think Ambassador Bolton has done a terrific job," White House press secretary Tony Snow said. "He's won over a lot of critics while building alliances on a range of issues, including Iran and North Korea, and working tirelessly to achieve meaningful results on reforms at the United Nations."

Speaking from prepared testimony, Bolton called for a "durable solution" to the violence in the Middle East and the need to "defang" Hezbollah.

"We are actively considering a variety of methods" to disarm Hezbollah, including establishing an international security force in the region, he said.

Bolton also said the United States remains committed to bringing peace to Darfur.

Bolton said some "modest progress" has been made in U.N. reform. "The goal now is to identify priority targets where progress can be made" and create a "lasting revolution of reform," he said.

Sen. Richard Lugar, chairman of the Senate Foreign Relations Committee, said Bolton exhibited "experience and accomplishment" and noted the Senate has already conducted an "exhaustive review" of Bolton's credentials.

By resubmitting Bolton's nomination to the Senate, the president has made clear "that Ambassador Bolton is important to the implementation of U.S. policies at the United Nations and to broader U.S. goals on the global stage," said Lugar, R-Ind.

Bolton has the green light from Sen. George Voinovich, R-Ohio, who last year sided with Democrats in opposing the president's nomination. While Democrats are still expected to oppose the confirmation, Bolton also has retained the support of other key GOP senators.