WASHINGTON -- The Senate is expected to vote today on President Bush's controversial choice of John Bolton to be the U.S. envoy to the United Nations.

John Bolton

While some Democrats were insisting last night that they might filibuster, both supporters and foes of Bolton expected that he ultimately would be confirmed, largely along party lines. The Senate has 55 Republicans, 44 Democrats and one independent.

Opponents of Bolton, now a State Department official overseeing arms control, have characterized him as a harsh critic of the United Nations and a "bully" with a history of trying to politicize intelligence and intimidate intelligence analysts who disagreed with his views.

Supporters have countered that Bush picked the outspoken, ideological diplomat to go to the United Nations because he has been a strong advocate for the world body's reform who "will get the job done" and put an end to corruption and inefficiency.

During a long day of heated debate, most criticism of Bolton came from Democrats, but one Republican was similarly outspoken -- Sen. George Voinovich of Ohio.

After a long speech about what he called the loss of U.S. credibility in the world and Bolton's harsh management style, Voinovich choked up and struggled to hold back tears as he asked for Bolton's defeat. He said too many senators didn't seem to understand how crucial the U.N. job was to America's image abroad.

"I know some of my friends say, 'Let it go, George, it's going to work out.' I don't want to take the risk," Voinovich said. "I came back here [to the Senate] and ran for a second term because I'm worried about my kids and my grandchildren. And I just hope my colleagues will take the time ... and do some serious thinking about whether or not we should send John Bolton to the United Nations."

Sen. Christopher Dodd, D-Conn., said he did not want a filibuster and would prefer an up-or-down vote on Bolton today, before the long Memorial Day recess begins. But he also said the Senate had a duty not to be deterred by the administration when lawmakers seek information about a nominee.

The two senior members of the Senate Select Committee on Intelligence issued dueling letters yesterday regarding their probe into sensitive communications intercepts examined by Bolton as undersecretary, the Washington Post reported. The Foreign Relations Committee had sought their help in obtaining access to the highly classified material and evaluating it.

Intelligence chairman Pat Roberts, R-Kansas, and ranking Democrat Jay Rockefeller IV, W.Va., agreed that Bolton did nothing improper in requesting the identities of U.S. citizens whose names had been censored in the communications intercepts. Bolton's opponents have speculated about his possible motives, but both senators agreed Bolton's requests were approved by the appropriate officials.

But the two men differed on Bolton's handling of the material in one instance, the Post said. Bolton spoke to an official named in an intercept -- someone who worked for him -- even though such communication was not supposed to take place. Rockefeller said the incident was worthy of more investigation. But Roberts said Bolton was not at fault because Carl Ford, the assistant secretary for intelligence, failed to warn Bolton not to share the information, even with someone with the necessary security clearance.

A compromise reached on Monday by Senate "centrists" to limit filibusters on judicial nominees does not apply to Bolton's nomination for the U.N. post. Dodd said that if the administration were to provide the intact intelligence information to four key senators, the threat of a filibuster would be dropped.

Senate Foreign Relations Committee Chairman Richard Lugar, R-Ind., said he also was satisfied that Bolton had done nothing improper in questioning intelligence analysis or requesting names of officials referred to in classified material.

While conceding that he was concerned about allegations that Bolton had behaved in a "blunt and combative" manner toward subordinates, Lugar nonetheless said Bush deserved to have his nominee approved because the U.N. job was vital to U.S. diplomacy and standing in the world.

Sen. Joseph R. Biden, D-Del., said that was the very reason he would vote against Bolton's confirmation. "Everybody acknowledges this guy is a loose cannon," he said.