In announcing his decision not to seek a fourth term as the District's mayor, Marion Barry made it clear last night that he intends to take an active role in annointing the next mayor, taking shots at some of the candidates and urging his supporters to wait before signing on with others.

"Don't go anywhere with anyone else until we can talk about it. That is my plea to you," Barry told supporters during a televised interview last night.

"We're still going to be a strong force in this town," Barry said. "I'm going to be out of it, but I'm going to live in Washington after this is over, and I want us to have a great town."

But how much influence Barry will have on this fall's election is uncertain. Members of his once rock-solid political organization, the strongest in the city, already have started defecting to other candidates.

Some politicians also questioned the value of a Barry endorsement and said it will be difficult, if not impossible, for the mayor to deliver his organization to a handpicked successor.

"It's very difficult for a politician to transfer his support to someone else," said D.C. Council member John Ray (At Large), one of the Democratic contenders for Barry's post.

Still, most politicians contacted last night said that Barry would continue to play an influential role in city politics, and that his quiet backing could be enough to push a candidate over the top in what is expected to be a very close Democratic primary in September.

"I clearly think the mayor can remain a force," said Kevin Chavous, a Ward 7 member of the D.C. Democratic State Committee. "He's been the most powerful elected official this city has had. That power is not going to disappear overnight."

"The mayor will have an impact on the direction of his supporters, but I expect to get much of that support anyway," said D.C. Council member Charlene Drew Jarvis (Ward 4), one of several Democrats seeking Barry's post.

Polls indicate that Barry maintains the support of 20 to 25 percent of the electorate, and activists say that Barry still commands the loyalty of several key constituencies, including senior citizens, government workers and people disaffected with the way the federal government has conducted its prosecution of Barry.

Although many of those people are expected now to begin lining up behind other candidates, others will wait for some kind of sign from Barry, whether overt or tacit, some politicians said.

One former Barry strategist estimated that Barry's word could still sway as much as 10 percent of the electorate, especially people living in Wards 4, 5, and 7, which are expected to be crucial battlegrounds in the coming election.

"They were wards which were strong Barry wards, and where he still would exert strong influence," the former strategist said. "Nobody wants him to openly endorse them, but in terms of quietly telling people in the wards and precincts what to do, sure that could make a difference."

"I have a strong feeling that he will be quite influential in this election," said African Methodist Episcopal Bishop H. Hartford Brookins, a friend of Barry's and an influential church leader. "His legacy will be his loyal constituency. Because of the great loyalty that they have to him, they will be inclined to listen to him."

To whom Barry would throw his support to is a matter of considerable debate. Ray has long been considered one of Barry's strongest allies on the D.C. Council, and some politicians believe he is the logical heir to Barry.

A recent poll by The Washington Post indicated that of all the current candidates, Ray would benefit the most were Barry to leave the race.

The poll, taken in May, showed that Barry and Ray led the pack with 23 percent of the Democratic vote apiece, with Ray's support climbing to 29 percent if Barry left the race.

Ray also has avoided some of the harsh attacks on Barry leveled by some of the other candidates. In a conciliatory statement last night, perhaps aimed at Barry die-hards, Ray said that Barry "has once again proved himself a man of courage" by taking himself out of the race.

Bob King, one of Barry's longtime political organizers in Ward 5, said last night he intends to support Ray now that Barry has officially declared himself out. "I think John is a solid person," King said. "He's a solid family man."

But Ray also has some enemies in the Barry camp, especially among some of the mayor's business allies, who believe Ray is untrustworthy, and among longtime Barry supporters who remember how Ray crossed the mayor by challenging him in 1982, after Barry helped engineer his selection to fill his vacant seat on the D.C. Council.

One Barry adviser said this week that Barry is seriously considering supporting Jarvis, who the adviser said embodied much of Barry's approach to constituent-service politics. "That would be the spiritual place for his organization to be," the adviser said.

D.C. Council Chairman David A. Clarke (D) also has argued that he stands to benefit if Barry gets out, noting his own civil rights roots and devotion to liberal causes. The other main Democratic contender, Sharon Pratt Dixon, has gone out of her way to distance herself from Barry, calling on him to resign while urging voters to "clean house" in the District Building.

Barry's decision could also be bad news for former police chief Maurice T. Turner Jr., a Republican mayoral contender, whose best chance at victory was capitalizing on anti-Barry sentiment, analysts said.

Barry once again took shots last night at his one-time ally, Del. Walter E. Fauntroy (D-D.C.), whose relationship with the mayor has been strained ever since Fauntroy jumped into the mayor's race in March, while Barry was seeking substance abuse treatment in Florida and South Carolina.

His remarks suggested that Barry will do everything in his power to block Fauntroy's mayoral ambitions. "Marion wouldn't support Walter for dogcatcher," said one longtime adviser. "He's furious with him."

Fauntroy was more conciliatory in response, saying he intends to "reach out to Marion Barry, the man, to be of assistance I can."

"I'm going to go out and work as hard as I can to earn each and every voter's support," he said. "You don't inherit support -- you earn it."