The District of Columbia Bar announced yesterday what it calls "a bold new effort" to recruit more lawyers to provide free legal assistance to the poor, whose needs have grown in recent years at the same time the federal government has drastically reduced funds for legal services.

In a letter mailed in April to the city's 55 largest law firms, the D.C. Bar, for the first time, sought specific commitments of 40 hours of free legal service a year from each lawyer in the firms. At a 50-lawyer firm, that would be roughly equivalent to a year's worth of legal service from one attorney.

"We probably have more private law firms per capita than anywhere in the country, but many of them don't pull their weight when it comes to pro bono work," said Elliot M. Mincberg, a member of the bar's public services committee. "The idea is to get them to do that."

At yesterday's annual bar conference, outgoing president Marna S. Tucker announced that 12 firms, including some of the city's largest and most prestigious, have joined the program as charter members.

In an interview, Tucker said the response was encouraging, given the newness of the recruiting program. "It's going to take more than just a letter," she said, adding that those who have signed up are generally "the same core group of people" who already provide free, or pro bono, legal service.

"The good thing is you can always count on them," she said. "The bad thing is they're making the other 75 percent of the bar look good, and I don't think that's how it should be."

Since 1978, the D.C. Bar, an organization to which all D.C. lawyers must belong, has funneled more than 3,500 pro bono cases to attorneys, coordinator Leslie Long said. The cases involve landlord-tenant disputes, problems of the elderly, employment discrimination cases and family issues such as divorce, child abuse and custody, she said.

But the program has been beset by a growing demand for services and a decline in budget and manpower. One section of the program sends clients to attorneys who promise to take at least two pro bono cases a year in exchange for receiving paying clients through the service. In 1980, that group included 275 attorneys. Now there are only 206, Mincberg said.

Meanwhile, the need for private pro bono attorneys has risen sharply, in part because of cuts in federal funds to the Legal Services Corp. In 1980, the Legal Services budget was about $321 million. It has dropped to as low as $214 million since then and is expected to be less than $319 million in the coming fiscal year.

Locally, Neighborhood Legal Services Director Willie E. Cook Jr. was forced to cut his staff by a third and shut down two offices in 1983. "The situation has deteriorated since then," Cook said. "We are struggling to keep our heads above water."

The private bar, he said, has been supportive, "but it is definitely not enough to fill the void."

The majority of the dozen firms signed up for the new bar program already do a good share of pro bono work. Covington & Burling, the city's largest with about 220 lawyers, pays three attorneys, two paralegals and two secretaries to work full time at Neighborhood Legal Services offices, according to coordinator Caryl Pines.

At Mincberg's firm, Hogan & Hartson, partner William Bradford supervises two attorneys who do pro bono work full time. Bradford said that joining the new bar program may act as a "magnet" for others. "If lawyers see a list of prestigious firms in the program, maybe they'll want to join too."