The question of whether Congress should approve funds for a convention center in downtown Washington has prompted fervent lobbying unlike any effort on a local issue in at least six years.

Is is the single most intensive lobbying campaign since 1971, when D.C. Appropriations Subcommittee Chairman William H. Natcher (D-Ky.) tried to hold Metro subway money hostage for approval for the Three Sisters highway bridge from Arlington to Georgetown, according to longtime observers.

Most of the money and power in town and most of the city's elected officials are on the side of building the center. Opposed to the center, or at least opposed to current plans for financing it, are a group of long-time civic activists and citizen association representatives. Four City Council members voted against the proposal, but only one, Douglas Moore, has been visible in efforts against it.

The Board of Trade, the D.C. Bankers Association, the Washington Board of Realtors, the Washington Hotel Association, and other major business organizations in town have been actively in favor of the center, which they say will be good for business. At their side, along with Mayor Walter E. Washington, City Council Chairman Sterling Tucker, Del. Walter S. Fauntroy (D-D.C.) and other lobbysists for the center, have been the city's major unions.

The city's major unions have called on their internationals the elaborate lobbying apparatus of the AFL-CIO for help in reaching members of the Senate, where a key vote is expected next week. The business community has sent its own representatives - such as Woodward & Lothrop president Edward Hoffman, realtor Foster Shannon, real estate attorney Robert Linowes and Board of Trade lobbyist Clarence Arata to Capitol Hill. And Mayor Washington has been reaching out in his own "low key" way, according to staff, telephoning and visitinh senators including Sen. Daniel Moynihan (R-N.Y.) and Sen. Charles Percy (R-III.)

Opponents of the convention center called a press conference yesterday to reiterate objections to the current proposal, objections outlined in a barrage of letters and memos to members of Congress in the past several weeks. They don't necessarily oppose the idea of a convention center, said several representatives of groups including the city's two major citizens association coalitions, but they want a referendum on the issue and a re-examination of the plant for financing a center.

"We feel the city does need a convention center, but we feel the question is important enough that it should be placed before the citizens," said Fred Thomas, president of the predominantly black. Federation of Civic Associations, a coalition of 57 neighborhood group. Adelene Bickerdyke, vice president of the other major coalition, the largely white Federation of Citizens Associations, which represents 26 groups, said her organizatiom has formally asked for a referendum.

Under D.C. law the Council can set a referendum but referendums cannot be initiated by voter action.

Both sides of the fight claim support for their point of view from the general public. "The center is needed, and yes, the citizens want it . . ." Mayor Washington said earlier this week. Opponents of the center had hoped to poll the city on the convention center issue but did not have the money, said Carol Gidley, an advisory neighborhood commissioner from one of three ANCs that have voted to oppose the current proposal.

"I was chagrined to note that until very recently no citizens groups supported the center," said Dick Wolf, president of the Capitol Hill Restoration Society, which also opposes the center. Several citizens groups signed a 3/4-page advertisement endorsing the center that ran in both Washington newspapers earlier this week, apparently largely paid for by business interests and unions. Two of the groups were in LeDroit Park, the Mayor's neighborhood, and one is the ANC in the Chinatown neighborhood near the convention center site. Others included the United Black Fund Inc., Voice of Informer Community Experssion (a group of business and community leaders) Far Northease-Southease Council and the Committee of 100 Ministers, an interdenominational group once active on civil rights issues and no active opposing legalized gambling and reduced panalties for marijuana possession.

Other citizens groups that line up in opposition to the convention center proposal include the Wisconsin Avenue Coordinating Committee, the Committee of 100 on the Federal City, and the upper Northeast Coordinating Council which organized originally to fight freeway construction through the city.