Sen. Biden of Delaware, the senior Democrat on the committee, read from a letter [Melody Townsel, a former contract worker for the United States Agency for International Development] had sent the committee, although he did not name her.

Ms. Townsel, whose allegations had begun to emerge in the news media , has said that for two weeks in 1994, when Mr. Bolton was working as a private lawyer for a subcontractor that clashed with her employer, he harassed her in a Moscow hotel, falsely claiming that she had misused funds and could face jail.

"'Mr. Bolton,'" Mr. Biden read from the letter, "proceeded to chase me through the halls of a Russian hotel, throwing things at me, shoving threatening letters under my door, and genuinely behaving like a madman. I eventually retreated to my hotel room and stayed there. Mr Bolton then routinely visited me to pound on the door and shout threats.'"

Senator Harry Reid, the Democratic leader, said today that Mr. Bolton's alleged comments to Ms. Townsel about possibly facing jail were "absolute lies."

John R. Bolton -- who is seeking confirmation as the next U.S. ambassador to the United Nations -- often blocked then-Secretary of State Colin L. Powell and, on one occasion, his successor, Condoleezza Rice, from receiving information vital to U.S. strategies on Iran, according to current and former officials who have worked with Bolton.

In some cases, career officials found back channels to Powell or his deputy, Richard L. Armitage, who encouraged assistant secretaries to bring information directly to him. In other cases, the information was delayed for weeks or simply did not get through. The officials, who would discuss the incidents only on the condition of anonymity because some continue to deal with Bolton on other issues, cited a dozen examples of memos or information that Bolton refused to forward during his four years as undersecretary of state for arms control and international security.

Bolton's time at the State Department under Rice has been brief. But authoritative officials said Bolton let her go on her first European trip without knowing about the growing opposition there to Bolton's campaign to oust the head of the U.N. nuclear agency. "She went off without knowing the details of what everybody else was saying about how they were not going to join the campaign," according to a senior official. Bolton has been trying to replace Mohamed ElBaradei, the director general of the International Atomic Energy Agency, who is perceived by some within the Bush administration as too soft on Iran.

John Bolton, President Bush's nominee for ambassador to the United Nations, desperately needs a haircut. It does not have to be a $600 Sally Hershberger cut. Bolton simply needs the basics. Tidy the curling, unruly locks at the nape of his neck, tame the volume at the crown, reel in the wings flapping above his ears, and broker a compromise between his sand-colored mop and his snow-colored mustache.

He needs to do this, not because he should be minding the recommendations of men's fashion magazines or grooming experts but because when he settled in before the Senate Foreign Relations Committee this week to answer questions about his record, his philosophy and his intentions at the U.N., he looked as though he did not even have enough respect for the proceedings to bother combing his hair -- or, for that matter, straightening his tie, or wearing a shirt that did not put his neck in a chokehold. Bolton was one wrinkled suit away from being an insolent mess.

Bolton sat across from his questioners with a thick, dull slab of hair positioned diagonally across his forehead. It is tempting to say that he has a sloppy schoolboy's haircut, but that would malign studious young men and suggest that they are dismissive of propriety and the importance of making a good public impression. Looking back to Bolton's school days at Yale, one notices that he was better groomed in his younger years. In his 1970 class book photo, Bolton essentially has the same haircut, but his locks are not drooping over his forehead as if he'd stepped from the shower and shaken his hair dry in the manner of an Afghan hound. His tie also appears to be straight. Thirty-five years ago, his shirt fit. (Perhaps it is the same shirt?)

They ticked off a number of treaties they said Bolton had opposed and said he had made "unsubstantiated claims" that Cuba and Syria were working on biological weapons.

Also, they said, Bolton once worked as a paid researcher for Taiwan and supported recognition of it as a sovereign state, and he was skeptical of U.N. peacekeeping operations.

"Given these past actions and statements, John R. Bolton cannot be an effective promoter of the U.S. national interest at the U.N.," the former diplomats concluded. "We urge you to oppose his nomination."