"Today ... we begin a political revolution. Today, we stand here and say loudly and clearly that enough is enough," Sanders said in front of a scenic backdrop of Lake Champlain in Burlington, Vt., the town he once led as mayor. "This great nation and its government belong to all of the people, and not to a handful of billionaires, their super PACs and their lobbyists."
Sanders' campaign launch before an enthusiastic crowd lured by his progressive message -- and perhaps the free Ben & Jerry's ice cream -- followed his more low-key announcement last month, which included just a news release followed by a brief Capitol Hill news conference.
In the time since, Sanders has emerged as a somewhat unlikely energizer of the part of the Democratic base cool to front-runner Hillary Rodham Clinton and uninspired by other potential hopefuls for the party's nomination, including former Maryland Gov. Martin O'Malley, who is expected to announce his own campaign Saturday.
Sanders, a self-declared socialist, reiterated his key issues -- income inequality, economic uncertainty, campaign finance reform and climate change -- and outlined what he called a "simple and straightforward progressive agenda" to deal with them.
Sanders said he would champion a $1-trillion infrastructure program that would create 13 million jobs, raise the minimum wage to $15 an hour, overhaul the tax code, strengthen regulations on Wall Street and overturn the Supreme Court's Citizens United decision on campaign finance that he said was "undermining our democracy."
He also proposed going beyond the Affordable Care Act to a Medicare-for-all system, as well as free public colleges and universal preschool.
"This campaign starting today is going to send a message to the billionaire class. And that is: You can't have it all," Sanders said. "To the billionaire class, I say, 'Your greed has got to end. You cannot take advantage of all the benefits of America, if you refuse to accept your responsibilities.'"
Sanders plans additional events as part of a kickoff tour in the early voting states of New Hampshire and Iowa and well as in Minnesota.
Clinton, who announced her candidacy in April, plans her first major public rally in mid-June.