D.C. Mayor Anthony A. Williams yesterday endorsed Council member Harold Brazil in the hotly contested race for Brazil's at-large seat, calling the veteran council member a "team player" who has contributed enormously to the city's economic revitalization.

Standing in front of Best Buy and the Container Store, two newly opened retail establishments on Wisconsin Avenue, Williams told a crowd of about 40 that Brazil's work as chairman of the council's Economic Development Committee has been instrumental in bringing quality development to the District.

"I want all of you to know this would not have happened, Best Buy would not have happened, the Container Store would not have happened, the Anacostia Waterfront development would not have happened, without the leadership of Harold Brazil," Williams said.

Williams (D) has so far declined to take a position in other contested council races. But yesterday he appeared with Brazil (D) for a news conference at the Tenleytown Metro stop, then accompanied Brazil as he knocked on two doors in the Tenleytown neighborhood, asking residents for their support.

At one point, the mayor wore a bright yellow hat that said "Harold Brazil."

"If you are evaluating whether you need to change horses or not, look at the record. And the record says stay with Harold Brazil," Williams said.

He then led the crowd in a chant: "Stay With Harold Brazil. Stay With Harold Brazil."

Brazil, who first won election to the council from Ward 6 in 1990, faces two serious challengers in the Sept. 14 Democratic primary. Kwame Brown, 33, the son of veteran D.C. Democratic activist Marshall Brown, has garnered an array of important endorsements.

And Sam Brooks, 24, a native Washingtonian and recent college graduate, has received high marks at candidate forums and from interest groups such as the Gay and Lesbian Activists Alliance.

Yesterday, Brown and Brooks downplayed the significance of the mayor's endorsement, calling it payback for Brazil's long history of voting with Williams on a variety of issues. Brazil is considered to be one of the most reliable votes for Williams's agenda among the 13 members of the council.

"Harold has always voted with the mayor on every single thing the mayor has wanted. So it's no surprise that he would endorse someone who's been a strong supporter," Brown said.

But Brown and Brooks also said the endorsement is unlikely to have much of an effect on the campaign -- and could actually hurt Brazil in some communities. In Tenleytown, for instance, local community groups are furious with the mayor for supporting dense development along upper Wisconsin Avenue.

Brazil, Brown and Brooks all appeared at a forum last night to discuss the issue. "These people are not happy with the mayor, and this endorsement can only hurt him with these people," Brooks said.

Brazil acknowledged that many Tenleytown activists are upset over the density issue. But he said Williams is nonetheless hugely popular in Ward 3.

"I am pleased. I see it as all upside," Brazil said of the mayor's endorsement.

Harold Brazil's opponents say endorsement may cost him voters.