WASHINGTON – With the Senate scheduled to seek a vote on the president’s nomination of John Bolton today, Democrats are threatening a last minute parliamentary maneuver to block the vote.

Yesterday Senator Dodd, a Democrat from Connecticut urged his colleagues to vote against the closing of debate on the floor of the Senate until the State Department provided him and his colleagues with outstanding requests for intelligence on a speech Mr. Bolton was blocked from giving on Syrian proliferation. Mr. Dodd also renewed a request from his party for the names Mr. Bolton requested of American officials in National Security Agency intelligence reports. Names of Americans are redacted in these files and are not disclosed unless requested by a senior official.

As the Senate began to debate the nomination yesterday, Democrats made a new allegation that Mr. Bolton inappropriately shared the identity of one such American official whose name he requested from the National Security Agency in a February 2002 report.

In a letter dated May 25 to the ranking Democrat and the chairman of the Senate Foreign Relations Committee, Senator Rockefeller wrote, “Mr. Bolton used the information he was provided in one instance in order to seek out the State Department official mentioned in the report to congratulate him.”

According to Mr. Rockefeller, a Democrat of West Virginia and vice chairman of the Senate Select Committee on Intelligence, the lapse in procedure jeopardized sensitive intelligence and was a serious enough violation to recommend voting against him.

However, the chairman of the intelligence committee, Senator Roberts of Kansas, hit back: “Is this the big problem where someone is alleging illegal activity?” Mr. Roberts said the standards for misconduct in this case were “nebulous.”

Messrs. Roberts and Rockefeller were shown the 10 separate intelligence reports requested by Mr. Bolton in his tenure as undersecretary of state from the National Security Agency with the names of the American officials blacked out. The briefings from the NSA were enough to satisfy Mr. Roberts, but Mr. Rockefeller has requested the identities of the American officials as well.

Mr. Roberts yesterday produced his own letter stating that Mr. Bolton’s requests for the officials’ identities were appropriate at the time. In addition, the letter said the director of the National Security Agency, Michael Hayden, concluded that they “were not only appropriate, but routine.” Mr. Bolton made 10 such requests in his tenure out of approximately 500 requests in the same period from other senior State Department officials.

In his letter, Mr. Roberts said the State Department’s Bureau of Intelligence and Research (INR), which is responsible for disseminating the NSA requests to senior officials at Foggy Bottom, never provided proper instructions for the handling of such sensitive intelligence requests.

“The NSA expects the INR to provide specific handling instructions at the time INR provides the identity to the requester,” Mr. Roberts wrote. “Not only did INR not provide such instructions to Mr. Bolton, it does not provide them to anyone.”

The official in charge of that bureau at the time was Carl Ford, the only official to testify in public against Mr. Bolton before the Senate Foreign Relations Committee, where he called the president’s nominee a “kiss up, kick down kind of guy.”

The latest allegations against Mr. Bolton appear to fit a pattern. Whenever the Senate Foreign Relations Committee sought to move Mr. Bolton’s nomination forward, new allegations emerged that Democrats said warranted more time for consideration of the president’s nominee.

Last month, when the committee first postponed a vote on Mr. Bolton’s nomination, Democrats argued in part that they needed more time to review allegations from a former USAID contractor, Melody Townsel, that the nominee in 1995 had chased her through the halls of a Moscow hotel and spread false rumors about her in Kyrgyzstan.

In later interviews with the committee’s staff, Ms. Townsel said she could not quite recall the exact details she shared in her letter to the Senate panel regarding the incident. Her supervisor at the time also disputed her account in a letter to the committee.

The latest charges over intelligence intercepts stem from a request from Senator Dodd, a Democrat from Connecticut, who in March asked Mr. Bolton about requests he made for the identities of American officials in the finished national security agency products.

At the time, Mr. Dodd alleged that Mr. Bolton may have sought those names in order to punish policy-makers with whom he disagreed. But even Mr. Rockefeller found no grounds for this accusation, which has been bandied about on Web logs opposing his nomination.

“Based on my personal review of these reports and the context in which U.S. persons are referenced in them, I found no evidence that there was anything improper about Mr. Bolton’s 10 requests for the identities of U.S. persons,” Mr. Rockefeller wrote in his letter.

As expected, Senator Voinovich, a Republican from Ohio, broke ranks with his party and gave a speech against Mr. Bolton. Mr. Voinovich forced the Senate Foreign Relations Committee in April to postpone a vote on Mr. Bolton after his Democratic colleagues aired Ms. Townsel’s charges and other matters. The committee eventually passed Mr. Bolton’s nomination on to the full Senate without a recommendation, a rare move.

During a 20-minute speech, at the end of which the Ohio lawmaker was on the verge of tears, Mr. Voinovich warned that Mr. Bolton would damage the president’s efforts to impose reform on the United Nations.

“Our enemies will do everything they can to use Mr. Bolton’s baggage to drown his words,” he said. Mr. Voinovich then cited testimony from Christian Westermann, the State Department analyst whom Mr. Bolton yelled at in 2002 over a dispute involving a speech about Cuba’s biological weapons program, and shared the opinions of numerous foreign service officers and foreign government officials about Mr. Bolton’s performance as an undersecretary of state.

The chairman of the Senate Foreign Relations Committee, Senator Lugar, a Republican of Indiana, urged Mr. Bolton’s confirmation and said most of the charges against him relied “on doubts arising from an intense investigation of accusations, many of which had no substantiation.”