PORTLAND — The Emanuel and Pauline Lerner Foundation has committed $25,000 to support the continued operation of the Portland Community Free Clinic, foundation and city officials announced Friday.

Lerner is challenging other foundations and community leaders to match its promised contribution, which will be made only if other groups or individuals come forward to match the Lerner grant.

Lerner is one of several Maine foundations that Mayor Michael Brennan has tapped in the hope of saving a critical community resource that’s in dire financial straits and may be forced to close early next year.

“When we learned of the impending fate of the Portland Community Free Clinic, every member of the Lerner Foundation board agreed that we needed to act right away,” Eliot Cutler, board chairman, said in a news release.

“Without access to health care, families and communities are at risk,” Cutler said. “The Free Clinic is a critical community asset that keeps its doors open because a remarkable group of volunteers provide care to their patients. It is important that we and other foundations step up now and help stabilize the Clinic and keep it open.”

Brennan thanked the foundation for stepping forward and making this commitment to the clinic and said he hopes other community leaders follow Lerner’s lead.

“This announcement couldn’t have come at a better time,” Brennan said. “Bearing in mind the current unpredictable landscape with in the health care system, it is crucial that as a community we come together to support programs like the free clinic, which ensures that the working poor have access to health care.”

The clinic at 103 India St. has enough cash to stay open until March, Brennan said. After that, it will need about $10,000 a month just to stay open through 2013, he said.

The city has long provided space and administrative oversight for the clinic, Brennan said, but it needs a long-term financial solution to weather economic turbulence caused, in part, by federal health care reform.

For nearly two decades, the free clinic was supported by the city and Mercy Hospital. In 2011, the hospital pulled its annual contribution of $210,000, citing shifting priorities and its belief that the city had other resources to serve similar patients.

The free clinic serves 500 to 600 patients annually from across Cumberland County, according to city officials. It targets people who earn too much to qualify for MaineCare, the state’s form of Medicaid, but who can’t afford health insurance or doctor visits.

The clinic is open from 6 to 9 p.m. Monday through Thursday, to accommodate people’s work schedules. Care is provided by doctors and nurses who volunteer their time. Patients can see both primary care doctors and specialists.

The clinic now has a yearly budget just over $100,000, which primarily covers wages of three part-time employees. The city kicked in $9,000 a month for July, August and September. The clinic is relying on reserve funds to carry it through February.

Another health care resource for low-income people is the Portland Community Health Center at 180 Park St. Started by the city, it will become a free-standing operation on Jan. 1, operating as a federally qualified, nonprofit health center, Brennan said.

Unlike the free clinic, the health center has a paid staff and serves people of all incomes, including those enrolled in MaineCare. Patients are billed based on their ability to pay, and the federal government provides grant support.

The city also operates the Health Care for the Homeless clinic at 20 Portland St., which provides medical, dental and mental health care for people who are living in shelters, cars or other unstable situations.