Seema Mehta / Los Angeles Times

WATERLOO, Iowa — Michele Bachmann formally kicked off her campaign for president on Monday in the town of her birth, as the Minnesota congresswoman seeking to parlay her Iowa roots and socially conservative credentials into a successful run for the GOP nomination.

“I seek the presidency not for vanity, but because America is at a crucial moment,” Bachmann said, speaking to supporters and reporters on the lawn of the Snowden House, a historic Victorian mansion not far from where she was born. “I believe that we must make a bold choice if we are to secure the promise of our future.”

The announcement was a formality; she declared during a June 13 debate that she had filed paperwork for a run. But the decision to announce in Iowa, where Bachmann lived until age 12, rather than the neighboring state where she currently resides and which elected her to Congress, served to emphasize the importance of the Hawkeye state.

A strong showing in the caucuses here, the first scheduled voting in the 2012 race, is vital for Bachmann’s chances. The 55-year-old tea party favorite has repeatedly stressed her Iowa roots on a two-day swing through the state, visiting the house where she grew up and the church where she was baptized, and talking about how she wept when her mother told her they had to move to Minnesota because of her father’s career.

A Bachmann radio ad that ran in Iowa last week proclaimed that the state “will always be home,” and she hosted a homecoming party Sunday where she implored attendees to support her at the Ames straw poll in August, an early organizing test of the GOP field.

“I need you,” she told hundreds of people at the National Cattle Congress on Sunday as they dined on pulled pork sandwiches and macaroni salad. “I came here because it’s all about Iowa.”

The timing of her visit was fortuitous. On Sunday the Des Moines Register poll of likely GOP caucus-goers showed her in a statistical tie with national front-runner Mitt Romney. Bachmann’s goal is to position herself as the race’s anti-Romney.

But while her candidacy is piquing the interest of voters, her campaign is still in its infancy. Competitors, notably former Minnesota Gov. Tim Pawlenty, have been campaigning hard here for months and have extensive teams in place.