The drawn-out labor dispute hanging over San Francisco's hotel industry is starting to have a serious economic impact, with more than 2,000 convention visitors this week canceling their visits and business interests blaming Mayor Gavin Newsom for the mess.

A gathering of 2,200 historians who were booked for four days at the San Francisco Hilton for their association's annual meeting has been moved to San Jose because of the contentious labor dispute roiling the city's hospitality industry.

The transfer of the meeting of the Organization of American Historians from the Hilton to San Jose comes as the hotel workers' union, in fruitless contract negotiations with 14 San Francisco hotels, escalates its boycott of the facilities in the hope that economic pressure will bring about a settlement. As a pressure tactic on the negotiations, the unions are calling groups headed for San Francisco, warning them of labor strife and asking them to remove their business from the hotels in the dispute.

Leaders of the union, Unite Here Local 2, had made it clear to the historians that "there is a good chance they are going to encounter a picket line'' if they went forward with the March 31-April 3 meeting at the Hilton, said Mike Casey, Local 2 president. The association then polled 900 presenters and other participants of the group's 98th annual meeting, and found that three-quarters said they would not cross a picket line.

"That would have destroyed the integrity of the meeting,'' Lee Formwalt, the association's executive director, said Thursday of the prospect of a meeting lacking core participants. The board eliminated other options -- remaining at the Hilton and canceling the meeting -- and moved the sessions to the San Jose McEnery Convention Center. Hotels, restaurants and other businesses in San Francisco will lose an estimated $1.8 million from a group of that size, according to the San Jose Convention & Visitors Bureau.

The executive board of the OAH, the largest professional organization for the study and teaching of American history, based in Bloomington, Ind., will also have financial exposure because of the move. Formwalt said there are some $60,000 in unbudgeted expenses because of the transfer, and he said the group, without an escape clause in its contract with the Hilton, will owe damages of $390,000. The group is negotiating the figure with the hotel, said Formwalt. A Hilton spokeswoman did not return a call for comment.

The association posted notice of the change on its Web site on Tuesday, but it has yet to remove a graphic showing the Golden Gate Bridge and other iconic San Francisco scenes.

As word of the loss of the large gathering of conferees spread, San Francisco Mayor Gavin Newsom came under attack by business interests because of the perception that his advocacy for the workers and his personal boycott of the 14 hotels involved in the labor dispute are supportive of the campaign to drive business away from the facilities and thus the city.

"We are extremely disappointed, and I think that the mayor by boycotting the 14 hotels does a great disservice to this city,'' said Linda Mjellem, executive director of the Union Square Association.

She added, "The mayor is someone I personally have a lot of resect for --

a person of principle and conviction and great passion. But I think this passion is counter-productive for the city. He is a mayor for all people, and I think that passion needs to apply for all people.''

Peter Ragone, a spokesman for Newsom, said the criticism is misguided since the historians did not make their decision based on Newsom's policy.

"We are not going to let criticism from either side stop us from doing our best to keep both sides talking and moving toward a resolution,'' he said.

Newsom, however, figured Thursday in a second move of business from a hotel. The San Francisco Business Times' fifth annual Mayors' Economic Forecast, featuring Newsom and Oakland Mayor Jerry Brown, was booked at the Hilton for Feb. 25. Publisher Mary Huss said Thursday that, knowing Newsom's policy not to go to the target hotels until the dispute is resolved and a contract negotiated, she asked his staff if he would attend an event at the Hilton. She was told he would not.

Some 1,000 people are expected for the Business Times' event, there is no other San Francisco hotel that could accommodate a group that large, so the newspaper moved the event to the Oakland Convention Center. "It was a business decision,'' said Huss. "I did not want to move the date for an economic forecast. I have sponsors. It's a financial decision.''

The transfer of the historians' meeting is a bonus for San Jose, which was damaged by the cancellation of the National Hockey League season in a barbed labor dispute. At the San Jose Convention & Visitors Bureau, Daniel Fenton, the president and chief executive, said, "It was clear (the historians) felt the unsettled labor situation caused their members concern, and therefore they felt San Jose was a great option for them. Because of the proximity, I think they feel it is a good match.''

In this case, the historians approached San Jose, but Fenton said his staff is identifying groups, like educators, where there would be a high degree of concern about an unsettled labor situation.

He added that the hotel labor dispute in San Francisco very likely would not occur in San Jose. Six of 27 board members at the Convention & Visitors Bureau are labor leaders, and the vice chair, Phaedra Ells-Lamkins, heads the South Bay Labor Council. "We have a philosophy that labor is a partner of ours, '' said Fenton.

Meantime, Casey, of Local 2, agreed that the boycott is costing San Francisco money, but said, "We are not going to give in until they give us a fair deal. We are asking for a very reasonable settlement, and the corporate owners (of the hotels) are fighting us tooth and nail.''

He said union members are making telephone calls to planners of events booked up to six months or more from now. He said he saw no hint of a settlement any time soon.

The 14 hotels, in a bargaining group, and Local 2 are at odds over wages, health care coverage, the length of a contract and other issues. There was a two-week strike against four of the hotels that began Sept. 29, after which the 10 other hotels in the group locked out their workers. The 4,300 employees at all 14 were locked out until Nov. 20, when the sides agreed to a 60-day cooling-off period and the workers returned. That has expired, and both sides say that neither a strike nor a lockout is imminent.

In addition to the Hilton, the other hotels in the group are the Argent, Crown Plaza, Fairmont, Four Seasons, Grand Hyatt, Holiday Inn Civic Center, Holiday Inn Express & Suites Fisherman's Wharf, Holiday Inn at Fisherman's Wharf, the Palace, Hyatt Regency, Mark Hopkins, Omni and Westin St. Francis.