City Councillor Sam Yoon's bid for mayor is already creating change. Tomas Gonzalez, former chief of staff for Mayor Thomas Menino, was helping create candidate Andrew Kenneally's campaign strategy to capture an at-Large seat on the City Council until this week.

"Not any more," said a glib Gonzalez Monday. "With Sam Yoon out and all these other factors I can't miss my opportunity."

Gonzalez is pulling together a strong team of political operatives to run against Kenneally and a gaggle of other council hopefuls for one of the two open seats left by Yoon and Councillor Michael Flaherty as they move to challenge Menino. The team so far includes lawyer Richard Lynds of East Boston; Debra Shah, who ran Sonia Chang-Diaz's successful campaign against incumbent Sen. Dianne Wilkerson; and Nurys Camargo, formerly of District Attorney Dan Conley's office.

Outside of saying he's definitely running, Gonzalez declined to comment further until later this week, when he plans to announce his decision.

The move could be troubling news for Felix G. Arroyo, currently enjoying a strong lead in fundraising and a reputation as a favorite due to name recognition tied to his father Felix D. Arroyo and his own work as a union organizer.

Gonzalez, with support from his former boss Menino and connections that result from serving as the city's Latino liaison for two years, would be in direct competition with Arroyo for the Latino vote, which is only part of the wide base of support that would be needed to win an at-Large seat.

As each candidate joins the race, Election 2009 is shaping up evermore as a banner year for candidates of color. Aside from Gonzalez and Arroyo, both Latino, Haitian Jean-Claude Sanon and African-American Scotland Willis have both said they are running, though the latter has yet to form a committee. Other candidates, such as African-American Ayanna Pressley, are considering a run as well.

Sam Yoon is also the first Asian-American to make a bid to be Boston's mayor.

Only three candidates of color ran for the at-Large seat in 2007, one of whom was Republican long-shot David James Wyatt. In 2005, Yoon and Felix D. Arroyo were the only candidates of color on the at-Large ballot.