D.C. City Council member Betty Ann Kane (D-At Large) launched her reelection campaign for a third term yesterday, saying that she has been a "strong, independent voice" on the City Council.

Kane, who has been a critic of Mayor Marion Barry's administration, said that the city "cannot afford to have a City Council that functions merely as a supporting cast to an executive branch performer. We must continue to have a City Council willing to be a watchdog of the executive branch."

She tried to challenge Barry in the 1982 mayoral primary but withdrew before the election because she could not get the necessary financial backing. Kane then easily defeated her opposition in the primary for the at-large seat.

Kane has drawn no significant opposition yet in the Sept. 9 Democratic primary, despite being among the council members targeted for defeat last year by tenant activists angry about her vote on rent control. Kane voted with the majority of the council to loosen some of the city's rent control provisions. City voters narrowly approved a referendum in November to overturn much of the council's rent control action.

"I listened when owners and tenants told me that even under rent control many people can't afford housing, and I pushed hard for a balanced rental housing law and the rental assistance program that has been funded this year by the council," Kane said at her announcement in the council chambers.

D.C. Board of Parole member John L. Gibson said yesterday that he was considering running for Kane's at-large seat as a Democrat. A group called Friends to Draft John Gibson Committee has filed papers with the D.C. Office of Campaign Finance.

"That draft committee has been out and really beating the bushes," Gibson said. "A number of people have said they would like to see my candidacy."

Political activists have said Kane would be difficult to defeat.

"She enjoys a broad base of support . . . . It would take a major misstep on her part for her to lose," D.C. Democratic State Committee Chairman James Christian said in a recent interview. He added that Kane had kept in touch with her supporters and was "most audacious" in going to parts of the city where her views are unpopular.

Four other members of the council -- Chairman David A. Clarke, Nadine P. Winter (D-Ward 6), H.R. Crawford (D-Ward 7) and Carol Schwartz (R-At Large) -- expressed their support for Kane at the announcement.

Clarke said that while he and Kane did not always agree on issues, she "plays by the rules fairly," has helped to build a stronger City Council and has taken on tough assignments. He noted her work on the city's cable television legislation and her oversight of the cable contract as head of the Public Services and Cable Television Committee.

Kane supported Schwartz in 1984 when she unseated the Rev. Jerry A. Moore Jr., a longtime Republican council member. Schwartz, who served on the D.C. Board of Education with Kane, said that she could not vote for Kane in the Democratic primary but intends to vote for her in the general election.

Crawford said that Kane "provided leadership . . . particularly for the underprivileged.