D.C. City Council Chairman Arrington Dixon yesterday called the District's embattled rent control law a failure that has not protected the poor, and said he would lead an effort to replace it with measures that would require major changes in the city's tax laws.

Dixon outlined the proposals at a Council committee hearing. Several of his colleagues said afterward it was the first time they had heard the proposals, and that they were not sure if they would support them.

The city's current rent control law expires at the end of next September. During yesterday's hearing, a spokesman for D.C. Mayor Marion Barry urged the Council to put off a quick decision by extending the current law through March 31 of next year.

City rent administrator Dorothy J. Kennison said the mayor is afraid any proposed law will become a battered political football if considered during the "supercharged" climate of the upcoming Council elections. The terms of six Council members expire next fall.

"A delay will provide time to analyze the issues more objectively," Kennison said. The mayor has set up a task force that is drafting a new bill.

Kennison said the mayor believes a "strong, fully-funded" rent subsidy program could eventually replace rent control laws.

Council Chairman Dixon proposed yesterday that lower-income tenants who pay more than 35 per cent of their income for rent be allowed to get tax credits. On the other hand, tenants who live in undefined "high rent" apartments could face rent increases of up to 25 percent a year.

Renters could deduct property taxes paid to the city, and lifetime tenancies would be provided for the elderly, under Dixon's proposals. A tax would be placed on rental units and condominium conversions, with conversions limited by ward.The city's current rent administrative bodies would be abolished.

The suggestion to delay a decision was greeted coldly by some Council members.

"I cannot believe some of this testimony," Council member Willie J. Hardy (D-Ward 7), who chairs the committee, told Dennison.

Barry "has highly-paid government persons on his task force and now he wants an extension," Hardy added.

"This chairman has no intention of moving to an extension. I'm a little disgusted with that kind of approach."

But two Council members later told a reporter that an extension of the current law indeed may be necessary, in order to give the Council enough time to review drafted bills and put together legislation that will not be overturned in court.

"We couldn't get through with a new bill in time, with the recesses," said Council member John Ray (D-At-Large). "At the moment, I see no realistic alternative to rent control."

With rental units comprising about 68 per cent of the District's housing, tenants can exert considerable influence on election day. Yesterday, tenant groups announced a major drive to register renters, and passed out a flyer outlining Council members' votes on tenant-related issues.

Tenants, with the support of 25 community organizations, also introduced their own lengthy rent control bill.

The tenant bill would place all rented units, except those in two-unit properties in which an owner resides, under the city's rent control law. It also would cover the cost of operating the city's Rental Accommodations Office by increasing rental registration fees, and would reduce the current Rental Accommodations Commission to a full-time, three-member agency, with a voluntary part-time advisory board.

A restructuring of the rent commission also was urged by a spokesman for the landlord industry yesterday.

John O'Neill, executive vice president of an organization representing owners and operators of 70,000 apartments in the city, wants a three-member commission of lawyers to hear cases brought by tenants and landlords.

In addition, O'Neill asked for decontrol of vacant apartments beginning next October, and the abolition of the city rental office. He suggested the city seek increased federal funding of about $20 million to fund a subsidy program for poor tenants.

Kennison told committee that the city lost 5,100 rental units between 1974 and 1977, most of it due to a decrease in rented single-family homes. The city's rental housing has further been depleted by condominium and cooperative conversions.