Catholic Charities, the county's leading provider of homeless services, is scrambling to come up with about $400,000 to offset the unexpected loss of federal grants that largely underwrite the nonprofit agency's shelter and services for homeless families.

The funding shortfall threatens operation of the 138-bed Family Support Center on A Street as well as a program that subsidizes rent for families that have been moved into permanent housing. Loss of the rent subsidies would create a bottleneck at the family shelter, keeping men, women and children there while other families remain in need.

The shelter's current waiting list — 53 families consisting of 64 adults, four pregnant single mothers and 91 children — could double if that happens, officials said Monday. Some people on the waiting list are living on the streets, they said.

"This was completely unexpected," said Len Marabella, a Catholic Charities board member who is filling in as the agency's executive director while it searches for a new administrator.

On June 16, the agency learned that it would not receive about $500,000 in Emergency Solutions Grant funding from the U.S. Department of Housing and Urban Development, a source that had consistently supported the family housing program for about 10 years.

"It was a shock to us," said Jennielynn Holmes, director of shelter and housing for Catholic Charities.

Immediate budget adjustments enabled the agency to pare the funding loss to $400,000, and the two officials said they are counting on support from local government, foundations and community donors to make up the loss.

Current funding for homeless family services expires July 11, and the Family Support Center, located at the former General Hospital, is full with 132 adults and children. The average age of people at the center is 12.

"We can't let the safety net for families fall apart," Holmes said.

Supervisor Shirlee Zane noted Catholic Charities' funding predicament during county budget hearings last week, and the matter was referred to staff for study.

"We don't want to see our homeless situation get any worse," Zane said Monday, calling the funding setback a "huge hardship" for Catholic Charities.

County officials are discussing the matter with Santa Rosa officials, and Zane said she expects a report back to the supervisors in July.

"The city and the county need to step up," she said.

Santa Rosa officials could not immediately be reached for comment Monday.

Zane said the county was also calling on Reps. Jared Huffman, D-San Rafael, and Mike Thompson, D-St. Helena, for help.

Catholic Charities is trying to find out from state and federal officials why the grant funding was pared, calling it an unprecedented development.

The funding shortfall does not impact Catholic Charities' two other shelters for single adults, 120-bed Sam Jones Hall in southwest Santa Rosa and 13-bed Nightingale shelter on Brookwood Avenue, or the Homeless Services Center, a drop-in center on Morgan Street.