UPDATED 11/20/10 – 5:35 p.m.

CHICAGO (CBS) — Former U.S. Sen. and Ambassador Carol Moseley Braun officially joined the race for Chicago mayor on Saturday.

She formally announced her candidacy to 2,000 supporters at Northerly Island, the site of the old Meigs Field, the airport Mayor Richard M. Daley tore down to create a nature preserve.

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Braun already has filed more than 91,000 signatures on her nominating petitions filed with the Chicago Board of Elections. Her campaign plans to focus on attacking frontrunner Rahm Emanuel and to try to exploit his legendary temper.

“When a guy like that’s buttons are pushed, we expect to see a reaction, and that kind of reaction we believe the people of Chicago are not gonna like,” Braun campaign strategist Mike Noonan said.

CBS 2 Chief Correspondent Jay Levine reports that it might be a risky strategy, just like kicking off her campaign outdoors on the Lakefront in November.

While Saturday’s gamble paid off with a Chamber of Commerce backdrop, going right at Rahm Emanuel is another matter.

Illinois State Sen. Martin Sandoval blasted Emanuel for leaving the White House to run for mayor.

“A month before the midterm elections, he abandons the president for his person ambitions and chose not to stand by our man Barack Obama. Is that the loyalty we want for Chicago? No,” Sandoval said.

Braun also took aim at Emanuel’s TV commercials that tell voters “We gotta decide whether we’re gonna continue to be a great city or become a second tier city.”

Braun said the ads “pose a completely false premise.”

“Let me tell you something else about us: Chicago will always be a great city because its people will tolerate nothing less,” Braun added.

There was no direct response from Emanuel, though a spokesman called his statement a “true reflection of the challenges the city faces” and that “instead of attacking his opponents, Rahm’s talking every day about … those challenges.”

Emanuel, President Obama’s former chief of staff, has not yet been endorsed by the President, though Obama has said Emanuel would make a great mayor.

John Rogers, who is one of President Obama’s best friends, is a Braun supporter and was at her campaign announcement Saturday.

Asked the significance of that fact, given his close relationship with Obama, Rogers said, “We haven’t talked about that. He’s busy running the country and leading the world, and I’m here to work with Carol and help her to become mayor of Chicago.”

Braun later joined supporters for lunch at a popular West Side restaurant, a move she said was an intentionally symbolic contrast to announcing on the lakefront.

“It’s all Chicago. That beautiful lakefront is Chicago, here on the West Side is Chicago, the North Side, the south, you know, we have to bring all the neighborhoods together,” Braun said.

But the West Side is traditionally the territory of U.S. Rep. and mayoral rival Danny Davis. For Braun to become one of the top two candidates to make the run-off in April, she’s got to do well in the race within the race; for the African American vote, against Davis and State Sen. James Meeks.

Other candidates in the race include longtime Daley aide Gery Chico; City Clerk Miguel del Valle; Rev. Wilfredo de Jesus; Jay Stone, son of Ald. Bernie Stone (50th); and relative unknowns M. Tricia Lee and Tyrone Carter.

Meeks is the only major candidate who has not yet filed his petitions. He’s expected to do so on Monday, the last day to file for the race for mayor.

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