By Glenn Collins

In an emotionally charged decision that some preservationists warned would set a precedent weakening protection for the city’s historic structures, the New York City Landmarks Preservation Commission voted 6 to 4 on Tuesday to approve the so-called hardship application of St. Vincent’s Hospital Manhattan.

The ruling clears the way for the razing of a distinctive 44-year-old building, which is crucial to a controversial $1.6 billion plan to build a medical tower and condominium in the Greenwich Village Historic District.

Although further approvals will be needed from city and state agencies — and at least one challenging lawsuit has been threatened — the vote was a victory for the hospital. It appeared to doom the building, the Edward and Theresa O’Toole Medical Services Building — a white, sawtooth-sided 1964 neighborhood monument that the hospital owns on Seventh Avenue between 12th and 13th Streets. It would be demolished to make way for the hospital’s planned medical tower.

Though once derided by neighborhood residents as the “overbite building,” preservationists have argued that the structure is an ornament to modern architecture that should be protected, and, as the onetime headquarters of the National Maritime Union, a historic vestige of the city’s nautical past.

The proposal seeks to demolish the O’Toole building and four others that the hospital owns in Greenwich Village to permit the construction of a 299-foot-tall medical building and a 233-foot-tall luxury condominium in conjunction with the Rudin Management Company.

“We take heart in the commission’s decision,” said Henry J. Amoroso, president of St. Vincent Catholic Medical Centers, the entity that includes the hospital.

Hospital officials have said that St. Vincent’s would have to shut its doors if it could not build a new hospital.

In May, the commission rejected the hospital’s application to tear down the O’Toole building under landmarks law. But the hospital reapplied under provisions that permit institutions to claim hardship as an excuse to demolish their buildings if they can prove that maintenance of the structures interferes with their ability to carry out their charitable purposes.

The hospital’s hardship request was quite rare. According to the commission, over the last four decades it has received only 17 applications — most recently 19 years ago. Before Tuesday, 12 of them had been approved.

Several commissioners said the decision was the hardest they had ever made, and one, Frederick Bland, who voted for the hospital’s application, said he woke up at 3 a.m. before the meeting to anguish over his vote, even journeying to the O’Toole building at dawn “for one last confirming look.”

The dissenting commissioners, who argued that the hospital had many alternatives to demolishing the O’Toole building, spoke to frequent applause from the audience of 100, which had braved driving rain and lashing winds to attend.

“It was an unusual vote for the commission, in that there were so many dissents,” said Peg Breen, president of the New York Landmarks Conservancy. She said that the vote could set a legal precedent, and that if it were challenged in court, “a decision will make landmarks law.”

Roberta Brandes Gratz, one of the dissenting commissioners, said that the vote “will absolutely set a precedent, because any nonprofit in any historic district can now seek to do the same.” She added, “We are on a very slippery slope, and I worry for our future.”

Some preservationists threatened lawsuits.

“We don’t believe that hardship was established in this case,” said Tom Molner, chairman of Preserve the Village Historic District. “We are going to challenge this in the courts. Constitutional precedent has been twisted to promote the interests of a private developer.”

But Gil Horowitz, speaking for the Washington Square-Lower Fifth Avenue Block Association, said that the community needed the hospital “and this is the best deal we could get.” He added, “There is no perfect solution here.”

William C. Rudin, whose family firm has teamed up with the hospital on the project, expressed pleasure at the commission’s vote, adding, “This is the city’s only hospital in a landmarked district, so it won’t set a precedent.”

Some residents have opposed the towers’ sizes, and have sought renovation of the existing hospital structures.

In May, after commissioners objected to the original development project, the hospital introduced a revised plan that lowered its proposed hospital tower and shortened the Rudin condominium — proposed for the east side of Seventh Avenue between 11th and 12th Streets — while saving four of the buildings that the hospital had wanted to demolish.

After the meeting, some said the O’Toole building was not necessarily lost.

“We don’t see the vote precluding the commission using its resources to search for an alternative site for the hospital,” said Kent L. Barwick, a former commission chairman who is president of the Municipal Art Society of New York, citing his own knowledge of landmarks law.

The commission will have more meetings about the architecture of the buildings on the site, and ultimately must approve them, along with the state Department of Health, the Planning Commission and the City Council.