As hopes dwindle for the Church of the Assumption, preservationists are frantically pursuing legal measures aimed at preventing a developer from starting demolition work Tuesday at the historic site linked to two of Philadelphia's Catholic saints.

The lawyer for the Callowhill Neighborhood Association, Samuel Stretton, said Monday he had made an emergency plea to a city building agency asking it to freeze the demolition permit. That agency, the Licenses and Inspections Review Board, is expected to consider his request Tuesday - the same day John Wei's demolition permit becomes effective.

The Callowhill neighbors say they were stunned last week when Wei obtained permission from the city to tear down the Spring Garden Street church, which played a significant role in the lives of two Philadelphians canonized by the Catholic church, St. John Neumann and St. Katharine Drexel.

The group has been in court since 2010 seeking to overturn a city decision allowing the church to be razed. They assumed the issue of demolition was on hold, Stretton said.

After the neighbors failed to secure a stay last week in Commonwealth Court, Stretton said, the group decided to turn to the review board. If it fails there, the ocher building will almost certainly fall to the wreckers.

Wei was initially seen as the building's savior. In July, he bought the 1848 church from a financially troubled nonprofit, Siloam, which had sought to demolish the church under the city's hardship rules. After taking over the property, Wei met with neighborhood residents to discuss ways to reuse the complex.

Wei said Monday that the city had forced his hand. He said he was preparing to renovate the rectory for apartments, but was denied a building permit because of structural problems with the church.

"I'm in a bad position. I don't have much money to fix the church," he said. "If I don't demolish, then I have liability."

Even if that's the case, Stretton argues, Wei still needs to petition the Historical Commission because the church is still, technically, a historically certified building. "We don't understand how he got the permit without going for review," he said.

But the city solicitor handling the case, Andrew Ross, said Wei did not need the commission's permission because Siloam had already obtained a demolition permit.

Wei said he was still unsure when demolition would start.

Contact Inga Saffron at 215-854-2702, isaffron@phillynews.com, or follow on Twitter @ingasaffron.