At a time when some District residents desperately need to find affordable housing and view the city government's Tenant Assistance Program as their best opportunity, a top housing official says the subsidy program could be forced to stop accepting new clients by the end of this fiscal year.

Such a change would be a real blow to thousands of low-income residents who pay a large percentage of their monthly incomes for rent and have been on a TAP waiting list since 1986 and to some homeless families who live in shelters and have received emergency consideration through TAP.

Under TAP, tenants pay 30 percent of their adjusted monthly income for rent and receive TAP certificates as proof that the city will pay the rest, provided the rent does not exceed a monthly payment standard established by the city.

Given the program's history (a failure to spend $7 million in budgeted funds in fiscal 1987 despite a waiting list of nearly 10,000) and a clear indication that it still has a future (a proposed $9 million budget for fiscal 1989), the warning seems premature.

But Alphonso Jackson, acting director of the Department of Public and Assisted Housing, insisted this week that the program could end this year. He said problems have been solved and the housing department is getting landlords, some of whom were once reluctant to participate, to accept tenants who have TAP certificates.

Jackson said the program is leasing about 100 new units a month and expects to have as many as 2,200 units leased by September. At that rate, the entire $9 million proposed TAP budget for fiscal 1989 would be needed to maintain leases, Jackson said.

If the program becomes as successful as Jackson predicts, it would be up to the mayor and the council to see that low-income renters continue to receive help by increasing the TAP funds for fiscal 1989. Where some council members are concerned, housing officials may have to overcome some doubts.

At a budget hearing before the council's Committee on Housing and Economic Development, council members dwelled on the underspending of the city's housing department.

Council member Charlene Drew Jarvis (D-Ward 4), chairman of the committee, and Council Chairman David A. Clarke (D) demanded explanations for underspending in major housing programs. During the hearing, housing officials acknowledged that the Department of Housing and Community Development failed to spend at least $9 million, including $1.8 million designated to help low- and moderate-income residents buy homes, budgeted in fiscal 1987.

Jackson said he viewed the council's budget questions as a signal that council members want more reliable housing budget projections and a higher standard of performance in meeting the needs of residents.

Jackson, who became acting director for the new public and assisted housing department last year, said he is confident that his department can not only meet the burden of proof but persuade the council to add more money for such crucial programs as TAP.Chorlton to Make It Official

District Council Journal editor Tom Chorlton, a former head of the Gertrude Stein Democratic Club here, is scheduled to join the growing list of council candidates today.

Chorlton, who has spent much of his public life in the Democratic Party locally and nationally promoting the rights of homosexuals, switched to the D.C. Statehood Party to improve his election chances. As a member of the Statehood Party, Chorlton, who wants to challenge incumbent Carol Schwartz (R-At Large) in the November election, faces a far smaller threshold of petition signatures to get his name on the party's primary ballot.

Chorlton had been scheduled to make his announcement last month but postponed it after Schwartz's husband's death. Chorlton will announce his candidacy at noon in Room 115 at the District Building, his campaign staff said.

Lawyer William P. Lightfoot, another former Democrat who has switched to independent to get on the November ballot, also is running for the Schwartz seat, but has not yet formally declared.

Schartz is being targeted in the November election because the District's Home Rule charter effectively prohibits the election of more than one at-large Democrat each two year cycle. Council member John Ray (D-At Large) is running for reelection and so far faces no announced opposition.