Republicans suffered a significant setback in their bid to hold on to the open Senate seat in Illinois as GOP nominee Jack Ryan yesterday tried to fight off calls to quit the race after allegations by his ex-wife that he had pressured her to perform sexually in front of other people.

The allegations were contained in documents from the couple's bitter custody battle four years ago were ordered unsealed by a California judge after the Chicago Tribune and WLS-TV sued to have them made public. Ryan, 44, denied the allegations and said he had no intention of dropping out of the race.

The GOP candidate, a millionaire former investment banker who left the business world to teach at a Roman Catholic school in the inner city of Chicago, already faced an uphill battle against Democratic state Sen. Barack Obama, with the most recent public poll showing Obama with a lead of about 20 percentage points.

The sensational allegations divided Republicans in Illinois and Washington. Rep. Ray LaHood (R-Ill.) called for Ryan to drop out of the race to help Republicans maintain their slim majority in the U.S. Senate. "I think it becomes very difficult for Jack to win," LaHood said in a phone interview.

Sen. George Allen (R-Va.), chairman of the National Republican Senatorial Committee (NRSC), gave Ryan his support. "Senator Allen talked to Jack this morning," said Dan Allen, NRSC communications director. "They had another good conversation. We're fully behind and fully supportive of Jack."

Ryan was married to television actress Jeri Lynn Ryan. In the documents released yesterday, she alleges that in the late 1990s, her then-husband took her to "bizarre clubs" in New York, New Orleans and Paris, where he asked her to have sex "and he specifically asked other people to watch."

Jack Ryan, in the documents, charged that his wife was trying to ruin his reputation with "ridiculous" allegations. Saying he had been "faithful and loyal" to his wife throughout their marriage, he said in the documents that he had arranged "romantic getaways" with her. He said they had gone to "one avant-garde club in Paris, which was more than either one of us felt comfortable with. We left and vowed never to return."

Some top Republicans in Illinois, including former governor Jim Edgar and the state chairman, Judy Baar Topinka, made clear through friends or advisers that they felt they were misled by Ryan, who had assured them in separate conversations there was nothing embarrassing in the court documents.

Edgar and Topinka declined to comment further yesterday as they and other GOP officials waited to see the fallout. House Speaker J. Dennis Hastert (R-Ill.) also declined to comment. Spokesman John Feehery said the speaker had not spoken to Ryan since the candidate held a news conference on Monday evening to answer the allegations.

Mike Lawrence, interim director of the Public Policy Institute at Southern Illinois University and former press secretary to Edgar, said the allegations would make it difficult for Ryan to wage a credible campaign against Obama for the Senate vacancy created by the retirement of Sen. Peter Fitzgerald (R-Ill.). "People are going to react instinctively to this, and I believe most of the reaction will be negative," he said.

Ryan's campaign spokesman said that, with the allegations public after months of rumors about what the documents contained, the candidate could begin to refocus his campaign on other issues and move forward.

"He's got the monkey off his back," Bill Pascoe said. "For months, there's been a whispering campaign about what's in the documents from political opponents. Now that the documents have been released, everybody can see: a, those rumors weren't true, and b, there's not an allegation that there was any marital infidelity, there's not even an allegation that he broke one of the Ten Commandments, there's not even an allegation that he broke the law."

Ryan said he had fought release of the documents to protect their young son. The Ryan campaign also issued a statement from his ex-wife in which she said, "Jack is a good man, a loving father and he shares a strong bond with our son." She added that he would make "an excellent senator."

Obama kept his distance from the controversy. Asked whether he believes the allegations are relevant to the campaign, he said in a phone interview, "I just think our campaign's going to focus on matters that are important to the voters and if we do, we'll do fine."

Republican Senate candidate Jack Ryan said he's staying in the race. Actress Jeri Lynn Ryan made allegations in divorce papers.