Former D.C. Democratic Party chairman A. Scott Bolden has decided not to run for District mayor and said yesterday that he is "90 percent certain" that he will challenge D.C. Council member Phil Mendelson for his at-large seat in 2006.

"I believe the best place for me to serve all of Washington right now is on the council," Bolden said in an interview at his K Street law offices. "We've listened to the voters and this is where they want me to serve. And I'm excited about it."

Since January, Bolden has waged a high-energy exploratory campaign for mayor, raising $200,000 and spending nights and weekends on an endless circuit of community events. His "listening tour" culminated this month when he commissioned pollster Ron Lester to conduct a citywide survey of 600 likely Democratic voters.

That poll found that, if the election were held today, about two-thirds of those surveyed would cast their ballots for Mayor Anthony A. Williams (D) or council member Adrian M. Fenty (D-Ward 4), the only challenger to formally announce his candidacy, Lester said. Bolden and the rest of the pack trailed far behind, with Bolden's support registering in the single digits.

More ominous, Lester said, just 20 percent of those surveyed even recognized Bolden's name -- too few to make him a serious contender in the crowded field seeking to replace Williams, who has yet to say whether he will seek a third term. Fenty's name, by contrast, was recognized by more than 60 percent of those surveyed, Lester said.

"Scott would have a lot of work to do to build name recognition" if he entered the race for mayor, Lester said.

Instead of taking on that daunting task, Bolden said he has all but decided to take on Mendelson (D). The at-large council member, who is serving his second term, has never won more than 50 percent of the Democratic primary vote, records show. Lester said Mendelson has prevailed only because multiple challengers split the rest of the vote.

Even better for Bolden, Lester said, Mendelson's name was recognized by only about half of those surveyed, making the race a more "level playing field."

"Mendelson is vulnerable," Lester said. "He has failed to build a citywide presence. We believe he has done some things very well and he's a good person. But Scott can provide better leadership on a citywide basis."

Mendelson said he welcomes the competition.

"It's a robust process when people are interested in running for office. People have a choice," Mendelson said. Still, he said, "it's awfully early in the season. What people say today may not hold up a year from now, when it counts."

Bolden, 43, a partner in the law firm of Reed Smith and a former president of the D.C. Chamber of Commerce, said he plans to make a formal announcement about the 2006 campaign by July 1. Bolden has appeared on the District ballot only once before: Last fall, he was ousted as Democratic Party chairman when his slate of candidates for the Democratic state committee was defeated. Lester said the down-ballot race attracted only 30,000 voters and is no measure of Bolden's abilities as a citywide council candidate.

By announcing his expected departure from the mayoral contest, Bolden becomes the second candidate to state his intentions. Fenty announced his candidacy June 1.

Council member Vincent B. Orange Sr. (D-Ward 5), who also has an exploratory committee, has scheduled a garden reception Sunday to announce his intentions. Orange has said he is "more likely than not" to run for mayor.

A fourth exploratory candidate, lobbyist Michael A. Brown, said he would decide this summer whether to seek the city's top job. Council Chairman Linda W. Cropp (D) and council member Jack Evans (D-Ward 2) say they, too, are considering campaigns.

"I'm excited about it," said A. Scott Bolden, former D.C. Democratic Party chair, of his likely run for D.C. Council.