Former City Council chairman Sterling Tucker's decision to enter this year's council chairman race was greeted warily in D.C. political circles yesterday, while his opponents showed off the kind of support that led some to wonder if Tucker had waited too long to jump in.

Tucker, meanwhile, promised to bring "excitement" to the race, and expressed confidence that he could erode the gains that the other candidates' campaigns have made.

Incumbent Chairman Arrington Dixon was endorsed by the D.C. Commerce and Industry Political Action Committee, the political arm of the Greater Washington Board of Trade, whose members so far have given $11,725 to Dixon, or about 15 percent of the $77,386 in contributions he reported June 10.

The other candidate in the race, council member David A. Clarke (D-Ward 1), was joined by leaders of the Metropolitan Washington Labor Council at a District Building press conference in which the labor leaders repeated their support of his campaign.

Initial reaction was that Tucker's candidacy was likely to draw some votes from Clarke but cut more deeply into Dixon's support.

In the past, Dixon and Tucker have drawn from a common base, centered among middle-class blacks in the Ward 4 area of upper Northwest, where Tucker lives and from which Dixon was twice elected to the council. In 1978, Tucker, then a candidate for mayor, supported Dixon when he was elected chairman.

Officials in Dixon's campaign said yesterday that a poll conducted in May showed Dixon "strongly" ahead of both Clarke and Tucker. They declined to release the poll results.

Some council members, asking not to be named, said yesterday they thought Tucker had waited too long to enter the race, while Dixon and Clarke have already locked up much of the available money and political support.

But former council member Willie J. Hardy, a longtime Tucker supporter, said she believes it is not too late for Tucker to win. She said support for Clarke and Dixon "may not be that firm," and added, "I can assure you that some of those people have been urging Sterling to run . . . and the commitments can change."

Aldus H. Chapin, head of the Washington Ballet and a leader of a committee that urged Tucker to run for an at-large seat on the council, said yesterday that he would support Tucker for chairman even though he had previously been supporting Dixon.

Tucker, who said he would be out of town until next Monday when he hopes to formally file his campaign papers, said yesterday he would announce his organization next week.

"I'm sure there's a lot of speculation. It's caused some excitement. The town needs some excitement."

Ivanhoe Donaldson, Mayor Marion Barry's campaign manager, said that Barry and Tucker have had several discussions recently, but that they dealt mostly with Tucker's efforts to negotiate a settlement in the dispute over the closing of the Anthony Bowen YMCA. He denied there was any "structural linkage" between Barry and Tucker.