"I am uniquely qualified to do the job of president, and I offer the clearest alternative to this current administration, whose only new idea has been pre-emptive war and a huge new bureaucracy," Braun said in a low-key appearance at Howard University. Her son, Matthew Braun, introduced her.
"A woman can fix the mess they have created, because we are practical, we are not afraid of partnerships and we are committed to making the world better for our children."
Braun stunned the political establishment in 1992 — the "Year of the Woman" — unseating an incumbent Democratic senator in the primary, two-term lawmaker Alan Dixon, on her way to what was once considered an improbable victory in November.
Her election was heralded as an advance for women and minorities, but her popularity fell amid accusations that she exercised poor judgment in visiting Nigeria's brutal former dictator Sani Abacha and misused campaign funds.
A campaign finance investigation cleared Braun, but she lost her seat to well-funded Republican challenger Peter Fitzgerald in 1998. After the defeat, President Clinton appointed her ambassador to New Zealand.
During her Senate years, Braun earned a 5 percent lifetime rating from American Conservative Union, and an 88 from the liberal Americans for Democratic Action.
According to the website run by her campaign, Braun opposes the war in Iraq, supports affirmative action and advocates a single-payer health care system.
Braun used her announcement speech to present her vision for the future — "an American renaissance" — and criticize President Bush's record on national security and the economy.
Braun said the United States will work to ensure a peaceful Iraq. "Americans don't cut and run, we have to see this misadventure through," she said.
Monday's kickoff schedule started with speeches at two historically black colleges — Howard and Benedict College in Columbia, S.C. Braun's final appearance was scheduled in her hometown of Chicago, where she got her start in politics 25 years ago with election to the Illinois Legislature.
During months of campaigning, Braun has struggled to build a fund-raising network. She has pleaded for financial support, especially when speaking to women's groups, but raised less than $250,000 in the first half of the year.
Last month, she picked up her first two major endorsements from the National Organization for Women and the National Women's Political Caucus. Leaders of both groups said they would help raise money for her among their members, and their support gave Braun encouragement to continue her bid beyond the exploratory phase.
Braun ranks near the bottom in most surveys, but some polls show her with more support than some of her better-financed rivals. She ranks higher in some polls of black voters.
She has avoided much of the intra-party fighting of her rivals who confront each other in an effort to rise to the top of the field. Her criticism has been focused on President Bush's policies at home and abroad.
"America is at a tipping point — if we stay the course we are on now, we won't recognize this country five years from now," she said in Monday's speech. "But if we shift gears, try another way, tap some of the talent that has been relegated to the sidelines of leadership, we can heal and renew and save our country."