WASHINGTON – The chairman of the Senate Foreign Relations Committee is confident his committee will approve the nomination of John Bolton for American ambassador to the United Nations in a 10-to-8 vote on party lines in the vote scheduled today.

Speaking to reporters outside the White House yesterday, Senator Lugar, a Republican of Indiana, said, “My hope and general prediction has been that we will have a motion that will bring John Bolton to the floor and that that will succeed.”

Mr. Lugar’s view was bolstered yesterday when a wavering Republican on the committee, Lincoln Chafee of Rhode Island, said he intended to vote for President Bush’s choice for the ambassador post.

The nomination of Mr. Bolton has been the most contentious of Mr. Bush’s second administration. Last month, an expected party line vote in the committee was delayed after Senator Voinovich, a Republican of Ohio, said he was not comfortable voting for Mr. Bolton, who is currently the undersecretary of state for arms control and international security affairs.

Speaking in Ohio to reporters yesterday, Mr. Voinovich said he had not decided how he would vote. When asked about comments by a White House spokesman who predicted a party line vote in favor of Mr. Bolton, Mr. Voinovich put a finger to his temple and said, “I don’t know how anybody knows what is going on in this guy’s head.”

The committee’s ranking Democrat, Senator Biden of Delaware, told NBC news yesterday he had not yet determined whether he would advocate a delay of the nomination vote, as he did last month. Democrats have complained that they have not received materials that they requested from the State Department in the last week, as both majority and minority staff looked into allegations that Mr. Bolton tried to punish analysts with whom he disagreed. Mr. Biden yesterday said the Republicans had not lived up to the terms of the deal he made last month that promised a vote following a more thorough investigation of Mr. Bolton’s record.

Democrats on the committee have tried to make the case that Mr. Bolton stretched intelligence and intimidated analysts by taking the word of the current undersecretary of state’s bureaucratic enemies. For example, the committee has interviewed a former American ambassador to South Korea, Thomas Hubbard, about a 2003 speech Mr. Bolton gave deriding North Korea as a prison state. At the time, a former secretary of state, Colin Powell, said the speech was cleared by his office and represented administration policy.

Earlier this week, the committee’s Democratic staff leaked declassified e-mail messages regarding Mr. Bolton’s alleged sidelining of the State Department’s Intelligence and Research Bureau’s assessments of China’s missile export control regime. On Tuesday evening, Reuters ran a story that claimed Mr. Bolton’s chief of staff, Fred Fleitz, expressed concern that the bureau included its dissent with Mr. Bolton’s view – shared by the CIA – that China’s export controls at the time were inadequate, in a memo to then deputy secretary of state, Richard Armitage.

The Democrats on the committee who leaked the memos may portray the exchange as another example of how Mr. Bolton, through Mr. Fleitz, tried to intimidate apolitical analysts simply performing their duties.

According to administration officials sympathetic to Mr. Bolton, the battle over Chinese missile exports was part of a nasty bureaucratic war. One such source said that the State Department’s intelligence analysts and nonproliferation experts attempted to stop Mr. Bolton from levying sanctions against three Chinese arms makers: CPMEIC, Norinco, and Zibo-Chemical. In 2002 and 2003, the three were alleged to have sold sensitive weapons technology to Iran. Memos were ignored, intelligence was not shared, and inventive legal arguments were employed by the State Department’s counsel, nonproliferation bureau, and intelligence shop to block Mr. Bolton’s wishes, the source said.

At the heart of the matter was a dispute over what constituted a transfer, or when Iran legally received the shipment that would trigger penalties under American nonproliferation laws and executive orders.

Mr. Bolton and his office believed that a contract between the Chinese concerns and the Iranians indicated that a transfer had occurred. The State Department bureaucrats, however, contended that intelligence had to prove the Iranians were in possession of the missile parts and prohibited materials, a far more difficult task for American operatives and informants. Without hard evidence that Iran was in possession of the material it had purchased, the bureaucrats argued, the Chinese companies did not technically violate the law.

Also at issue are 10 National Security Agency intercepts for which Mr. Bolton requested the names of Americans blotted out from summary reports. Senator Dodd, a Democrat from Connecticut, has alleged that Mr. Bolton requested the names of American officials in order to blackmail rivals in the Bush administration. Mr. Bolton told the committee in March that he made the requests in order to have a more complete understanding of the intelligence.

As a compromise, the National Security Agency has briefed the chairman and ranking member of the Senate Select Committee on Intelligence. Senator Roberts, the Republican from Kansas who chairs the intelligence panel, is expected to provide his assessment of the intelligence to the committee this morning, according to a spokesman for the committee.

Yesterday, Mr. Lugar said he believed the intelligence transcripts would not affect the vote. “My own personal view, and this is not one shared by other senators on the committee, is that, at this point, that is not consequential to the vote we’re going to have on Mr. Bolton,” he said. “In other words, the eight Democrats on the committee have indicated strong opposition. Maybe whatever they learn makes them stronger.”