Hard-pressed urban-aid lobbyists have launched a major effort to rescue another large-scale federal program they say they have no way to replace: construction and maintenance of subsidized housing.

The National League of Cities is trying to break a deadlock in Congress that has left the federal government with no program for expanding its stock of low-income housing for the first time in 45 years. The impasse also means that no new low-income families are receiving rental subsidies under the Section 8 program.

The Reagan administration, trying to eliminate most new construction of subsidized housing, has given only nominal support to continuing these programs at reduced levels. But the League of Cities has joined several labor and industry groups in urging Congress to approve about $10 billion in housing assistance during the lame-duck session.

Even if the House and Senate agree on the $10 billion figure, it would be only about half the level of federal housing aid in previous years. This comes at a time when record interest rates, high rents and low vacancy rates have created a shortage of affordable housing in many areas. Many of the hundreds of existing public housing projects have long waiting lists and have become increasingly expensive for local officials to repair.

"It looks like part of an overall strategy for the federal government to get out of the public housing business," said Cathy Reynolds, a Denver council member. "Very few cities have the capability to do that building on their own, but the need has not gone away. We feel a little helpless."

Reynolds was hardly encouraged when a senior federal housing official told the League of Cities conference in Los Angeles last week that the administration is determined to cut subsidies for public housing and to stop building low-income projects for the time being.

James Baugh, deputy assistant secretary of Housing and Urban Development, said that for some deteriorating projects, "in the long run it's better to demolish it, sell it off or whatever." He called this "an innovative idea."

As for the $1.2 billion a year HUD now spends to help run public housing projects, Baugh said, "We're doing everything we can to make sure we reduce operating subsidies."

Baugh said HUD should build no new projects until it can improve conditions in properties the department has financed. "We have a debt service there, and we want to make sure we collect on the money," he said.

Some cities have been forced to take small steps on their own. Seattle recently approved a $48 million bond issue to build 1,000 low-income units for the elderly, but this will meet only a fraction of the need.

"Housing is the greatest unmet need in my city," Mayor George Latimer of St. Paul, Minn., said. "There isn't any question it's a national responsibility. I don't know of any serious person who claims the private sector can respond to the needs of housing the poor. That isn't where the profit is."

Other mayors would be happy to see the controversial programs disappear. "We have built very few public housing units," Mayor Bob Bolen of Fort Worth, Tex., said. "We've had a tremendous resistance to it. Our people are willing to pay for basic services, but they don't want any frills."

Alexandria Mayor Charles Beatley, vice chairman of the league's housing committee, said federal operating subsidies for public housing may be reduced just when his city's 40-year-old projects are in dire need of repair.

"The federal government shouldn't let public housing authorities go down the drain," he said. "There are people on the bottom of the totem pole who will not have a place to sleep."

Beatley noted that homeowners and builders receive millions of dollars in tax benefits. "Middle-income housing has received substantial subsidies, but it's hidden," he said. "What they're really saying is they don't want to help poor people."

HUD is considering a new method of financing public housing that could cut subsidies to the 200 largest housing authorities by 10 percent or more a year.