Luke Thomas/Fog City Journal

David Chiu, left, announces his mayoral candidacy Feb. 28, 2011 as Supervisor Eric Mar looks on

David Chiu, the president of the San Francisco Board of Supervisors, announced his candidacy for mayor on the steps of City Hall Monday, casting himself as the agent of a new era of civility and collaboration in San Francisco politics.

“Over the past 10 years in City Hall we’ve had way too many moments when our mayor and our supervisors haven’t been able to work together, haven’t been able to do the people’s work,” he told a crowd of about 100 supporters and reporters from all of the city’s major news media outlets. “I’m so proud that now, in my second term as the president of your Board of Supervisors, the tone at City Hall has changed,” he said.

The first-term supervisor vowed to ride the same spirit of inclusiveness to the mayor’s office by forming a sweeping coalition of support, beginning with community events scattered throughout the city. He was flanked by supporters representing public transportation advocacy groups, Polk Street neighborhood organizations and Chinatown nonprofits.

“Look around,” Chiu said with a grin. “We are San Francisco.”

Chiu’s platform was similarly broad, as he pledged to boost San Francisco, which he called a “beacon” of diversity and innovation, by creating jobs, although he offered few details on how he planned to do that.

Chiu, who has long touted the fact that he does not own a car and rides his bicycle to work, said the city’s public transportation system must be improved and the roads “throughout the city” made more bike-friendly.

“We’re sick of gridlock. We’re sick of potholes. And we’re sick of Muni,” he said.

Supervisor Eric Mar of the Richmond District appeared alongside Chiu to offer his endorsement.

Chiu has been expected to enter the race for several months. He is regarded by political analysts as one of the strongest contenders, along with state Sen. Leland Yee and City Attorney Dennis Herrera.

He has hired Josh Pulliam, a Sacramento-based consultant with extensive experience working with labor unions, as his strategist. David Latterman, a San Francisco consultant who has generally worked for politically moderate candidates, will also advise Chiu.

A native of Boston with three degrees from Harvard, Chiu moved to San Francisco in the 1990s and worked as a prosecutor and as a staff attorney at the Lawyers' Committee for Civil Rights, a nonprofit organization.

He also founded Grassroots Enterprises, a political communications company.

Chiu was elected to the board in 2008 and was voted board president during the first session of his term. He retained the presidency this January after helping orchestrate the appointment of interim Mayor Edwin M. Lee.