Representatives of Washington's business, banking and real estate interests urged the City Council yesterday to scrap major provisions of the city's condominium conversion law, including the right of most tenants to vote on whether their buildings should be converted.

In addition, the business groups opposed a new proposal to grant "life tenancy" for elderly renters in converted buildings, and suggested that the council reduce the time allowed for tenants to purchase some buildings that are to be converted.

The proposals met with a cool response from several City Council members and an audience of about 150 persons at a District Building public hearing on the issue.

Council member John A. Wilson (D-Ward 2) proposed the life tenancy provision in a bill that would grant a five-year extension of the condominium conversion law, which will expire Sept. 10. Wilson's measure has seven cosponsors.

Under Wilson's bill, vacant buildings would be exempt from the conversion ban if developers set aside 35 percent of the units for low- to moderate-income residents.

The current law prohibits conversion of any building that has become vacant since January, 1980; requires that 51 percent of the building's tenants approve a conversion; and mandates that the tenants be given the right of first refusal to buy the property.

Carol B. Thompson, director of the Department of Consumer and Regulatory Affairs, said Mayor Marion Barry's administration does not support life tenancy, though it does support the "general intent" of Wilson's bill.

Thompson, who said a total of 249 elderly persons have been protected from displacement in 61 converted buildings, said the mayor favors the current procedure, which allows elderly persons in affected buildings to continue to rent only during the statutory life of the conversion law.

"That's like a stay of execution," one tenants' rights activist said after the hearing.

Realtor Flaxie M. Pinkett told the council that the conversion law has been "excessive" and that real estate interests "all feel we are facing a very unstable situation . . . there are a powerful lot of places vacant."

Pinkett, slated to become the next president of the Greater Washington Board of Trade, represented the board, the D.C. Bankers Association, the Washington Board of Realtors, the D.C. Builders Association, the Metropolitan League of Savings Institutions and the Apartment and Office Building Association.

About two dozen individuals and representatives of tenants' groups were scheduled to testify in support of the bill.

Joseph Senturia, president of the Brandywine Tenants Association, said too many elderly residents face "the trauma of advanced age and of being faced with relocation or financial complications" resulting from condominum sales.

Pinkett suggested that the city's restrictions on conversion apply only to buildings in which rents are among the lowest 25 percent charged in the city--a plan she said would protect low-income persons from conversion.

The plan would eliminate the right of tenants in the remaining 75 percent of buildings to decide by vote whether a conversion will proceed.

Wilson told Pinkett that he is "unalterably opposed" to the plan she described, but said there is "room for discussion" on what to do about the city's vacant buildings.

"We have never supported the law on the basis of just protecting low incomes," Wilson said in an interview, adding that the law is needed to keep affordable rental housing in the District.

Wilson's bill is cosponsored by Chairman David A. Clarke, Hilda Mason (Statehood-At Large), Jerry A. Moore (R-At Large), Frank Smith (D-Ward 1), Polly Shackleton (D-Ward 3), William R. Spaulding (D-Ward 5) and Wilhelmina J. Rolark (D-Ward 8).