Democrat Howard Dean (search), a favorite of anti-war liberals, formally announced his presidential campaign Monday and immediately sought to expand his appeal by recasting himself as a populist fighting Washington insiders and corporate America.

The former Vermont governor, who has evolved from a pro-business centrist to a popular candidate of the left, urged voters to overcome their "profound fear and distrust" of the political system and stand against President Bush.

"You have the power to take back the Democratic Party! You have the power to take our country back!" he said. "You have the power! You have the power!"

The fiery rhetoric brought roars from the crowd of at least 2,500 crammed into a red-brick pedestrian mall, a church steeple towering behind Dean. The crowd was five times larger than announcement events staged by presidential rivals Dick Gephardt and Bob Graham.

Hundreds more supporters watched the speech at campaign sites across the country, a sign that Dean is building a formidable, Internet-driven organization.

Dean's newly fashioned message puts him in lockstep with Gephardt, a Missouri congressman, and Sen. John Edwards of North Carolina. Both cite their humble upbringings and vow to "fight for ordinary people" -- a line borrowed by Dean.

Dean hopes to galvanize Democrats who have not voted in recent elections, as well as independents who rallied behind insurgent candidates such as Republican Sen. John McCain (search) in 2000 and Democrat Gary Hart (search) in 1984.

The strategy is part of a career-long evolution.

The 54-year-old married father of two -- his wife, Judy, is a fellow physician -- built a centrist record during his 20 years in Vermont government, the last 12 as governor.

He battled Democrats to limit spending and balance the state budget, even pushing for cuts in human services programs such as benefits for the aged, blind and disabled. He nominated tough-on-crime judges, most of them former prosecutors. And he imposed work requirements on welfare recipients well before former President Bill Clinton (search) did.

As governor, some of his strongest supporters were Republican leaders in the business community. Difficult to label, Dean once called himself "an odd kind of Democrat."

In the early going of the presidential race, Dean courted liberals who believed their party leaders were too soft on Bush. The key has been his opposition to the U.S.-led war against Iraq, a position that boosted Dean into the top tier of polls in the early voting states of Iowa and New Hampshire.

He kept up his attacks Monday, arguing that Bush has divided Americans on race and gender issues, creating an "insurmountable debt" and cutting taxes to the rich in a policy "designed to destroy Social Security, Medicare, our public schools and our public services."

"This president has forgotten ordinary people," he said.

Dean said Bush and his "narrow-minded ideological advisers" have embraced a dangerous brand of go-it-alone foreign policy.

But Dean said he would "take up arms in the defense of our nation," if necessary, as president -- an answer to critics who say he is not ready to be president.

He did not help himself with an uneven performance Sunday on NBC's "Meet the Press." Dean stumbled over questions about the size of the U.S. military and the stability of Social Security.

In his speech Monday, he did not dwell on his anti-war position nor his moderate record in Vermont. Instead, Dean sought to widen his appeal by portraying himself as a blunt-speaking, anti-establishment candidate who places reform above any single issue.

He said he began the race pushing health care and children's issues above all, but his focus has shifted -- a rare concession for a politician.

"Something changed along the way as I listened to Americans around this country," he said. "Everywhere I go, people are asking fundamental questions: Who can we trust?"

He said companies are dodging taxes and paying poor wages -- all with the support of "a political process in Washington that they rent -- if not own."

He reissued a warning from James Madison and Thomas Jefferson who spoke of the fear "that economic power would one day try to seize political power."

Not on his watch, Dean said.

Besides a crowd here that spilled from an intersection into two nearby streets, 15,000 Dean supporters had signed up to attend campaign events in more than 300 cities.

It was impossible to verify Dean's projections, but in one city, Des Moines, Iowa, 87 supporters signed up to watch his address at campaign headquarters; 47 showed up.

"It's a good way to get out of the office," said Des Moines lawyer Ben Stone. "I spend too much time at my desk."

Sally Troxel was a bit more bubbly.

"I want to help build momentum with all the excitement," she said. "I like to be in the middle of it."

A crowd estimated by supporters at 670 packed a coffee shop in Austin, Texas, to watch a replay of Dean's announcement.

"I think I'd like to see a regime change in my own country," said Marcus Ollington, a cartographer who believes President Bush misled the public about the reasons for going to war.