In an era in which running for the nation's highest office has become a vehicle for self-promotion for some, Sanders' kickoff was a classic underdog pitch to draw greater attention to his chief issues, economic inequality and a political system increasingly tilted to the well-off.
"This campaign is not about Bernie Sanders," the rumpled 73-year-old said at a news conference outside the Capitol. "It is about a grass-roots movement of Americans standing up and saying: 'Enough is enough. This country and our government belong to all of us, not just a handful of billionaires.'"
"The major issue is, how do we create an economy that works for all of our people rather than a small number of billionaires?" he added.
Sanders, the longest-serving independent in the history of Congress, will campaign for the
"The reality is that if you want to engage in debates, if you want to mobilize people, it is hard to do it outside the two-party system," he told CBS News.
His entry makes him a leading potential challenger to former secretary of State and party heavyweight
Already, the influence of Sanders and other prominent liberals like Sen. Elizabeth Warren (D-Mass.) has appeared to influence the early days of Clinton's campaign. She has vowed to be a champion for the working class, and her kickoff video noted that while Americans "have fought their way back" from the Great Recession, "the deck is still stacked in favor of those at the top."
"I agree with Bernie," Clinton said in a tweet welcoming him to the race. "Focus must be on helping America's middle class. GOP would hold them back."
Sanders was elected as Vermont's lone House representative in 1990. During his eight terms, he was embraced by his state's Democratic Party, which didn't field a candidate in either his 2006 or 2012 campaigns for Senate.
In Congress, Sanders has advocated for higher taxes on the wealthy and increasing the minimum wage, and is a lead opponent of President
Sanders also voted against the 2002 authorization that paved the way for the Iraq war. Clinton's vote for that resolution figured prominently in her 2008 presidential run against Obama.
A national Quinnipiac University poll conducted in mid-April showed Clinton leading the race for the Democratic nomination with 60% support from primary voters. Sanders polled at 8%, just behind Vice President
But recent surveys from Public Policy Polling, a Democratic-leaning firm, showed Sanders cracking double-digit support in the early nominating states of Iowa and New Hampshire.
Still, the polling firm's director, Tom Jensen, said Clinton's front-runner status appears secure.
"He does have a chance to pick up enough support to bring attention to his issues and be part of the conversation," Jensen said of Clinton's first announced opponent for the nomination. "Certainly Sanders is more serious than O'Malley, Webb and Chafee because he has a real message and the credibility of being a big voice on the left for decades now."
Candidates who occupy the role of forcing others to speak to issues that may be uncomfortable for them, a position Sanders is likely to ultimately end up in, are a time-honored tradition in politics. Among Republicans, Sen.
Sanders made no mention of Clinton in his remarks to reporters or in an email announcement to supporters. “This is not the Red Sox versus the
"In a democracy, what elections are about are serious debates over serious issues, not political gossip, not making campaigns into soap operas," he said.
In response to reporters' inquiries, though, Sanders said questions swirling about donations to the Clinton Foundation were a "fair issue," but not one that he was most concerned with.
"What is more fair game to my campaign is the role of money in politics," he said, specifically attacking the billionaire Koch brothers' influence in Republican politics. "I wonder now in this day and age whether it is possible for any candidate who is not a billionaire or who is not beholden to the billionaire class to be able to run successful campaigns. If that is the case, I want you all to recognize what a sad state of affairs that is for American democracy."
Sanders said he would run a "vigorous" campaign that would rely on small donors to sustain it.
"We're in this race to win," he said. "If you raise the issues that are on the hearts and minds of the American people, if you try to put together a movement … that's not raising an issue, that's winning elections."
After his news conference, Sanders returned to the Capitol for Senate business. He will travel to the early primary state of New Hampshire this weekend for his first events as a candidate. He also plans a larger kickoff event in his home state in May.