PORTLAND – As the temperature drops and social workers comb wooded campsites and parks to encourage the homeless to come in from the cold, city officials are pressing for more of a statewide approach to the problem of homelessness.

Most of the people in Portland’s shelters come from outside the city.

“We remain the only city in the state that operates homeless shelters, and we are the only homeless shelter system that has developed an emergency overflow plan,” said Gerald Cayer, director of Portland’s Health and Human Services Department.

Besides the availability of health care and food, some homeless people gravitate to Portland because shelters in other communities turn people away when they reach capacity or when the clients exceed the maximum allowable stay, Cayer said.

“As a community we remain committed to running a low barrier shelter because we don’t want people sleeping outside,” he said. Heavy use of city shelters and other homeless services in recent months has some advocates wondering whether Portland can handle the growing problem.

In the short term, city officials say shelter capacity should be adequate for the winter, though the overflow plan is in place should demand exceed capacity.

The city’s Oxford Street Shelter, the primary emergency shelter for adults, reached its capacity of 154 five times in September and seven times this month. The Milestone Shelter, for adults with substance abuse problems, was at or beyond its 29-bed capacity all but six days in September.

But so far, the city has not had to resort to its overflow plan, which calls for opening the lower level of a Salvation Army facility. The overflow plan would be staffed with help from the United Way, the American Red Cross and the Preble Street Resource Center. Preble Street Resource, a nonprofit agency that runs a soup kitchen and offers counseling for poor people, has seen demand for its services grow sharply in recent months.

“We’ve seen over 300 people in an hour and a half for breakfast several mornings for the last few weeks,” said Mark Swann, the center’s executive director. The soup kitchen typically serves 240 people, he said.

“We’re pretty nervous about the upcoming winter. … This is not just Portland, Maine. We’re calling all around the country and talking to our peers and everyone is facing this kind of increase.”