A one-horse race no more.
Sen. Bernie Sanders (I-Vt.) will formally enter the Democratic presidential primary contest Thursday, as first reported by Vermont Public Radio. He plans to release a brief statement in the next 24 hours with a campaign kickoff event to follow in the coming weeks. Sanders, an independent who caucuses with Democrats on Capitol Hill, has been publicly flirting with a decision since the end of last year.
Sanders' arrival on the trail represents the first meaningful challenge to Hillary Clinton and her rich, barnstorming campaign. It also means the former secretary of state will be buffeted on the left by a formidable and popular liberal opponent. Former Maryland Gov. Martin O'Malley is pursuing a similar route, but has failed to crack 1% support in the early polls and seems disinclined to criticize or question Clinton head-on.
For Democrats, Sanders' decision to join the fight guarantees at least one fiery progressive foil will be sharing the debate stage with the frontrunner, as Sen. Elizabeth Warren (D-Mass.), another grassroots favorite, seems content to have her say from the peanut gallery.
Why he's running: Speaking with Bill Moyers in October, Sanders, though still undecided at the time, laid out his argument in stark terms.
"Things are getting worse," he said. "When you look at this campaign, and you realize the enormously serious issues this country faces, right — we got a collapsing middle class. We have more wealth and income inequality today than we've had since the 1920s. We have all of these enormous issues. And what big money can do is put an unbelievable amount of TV and radio ads out there to deflect attention from the real issues facing the American people."
Those "real issues" include, to wit: moving past Obamacare to single-payer health insurance funded by tax hikes on millionaires and billionaires; free college for anyone who wants to attend; a radical redrafting of trade policies he believes devalue American workers; and a new push for a constitutional amendment that would reverse the Supreme Court's Citizens United decision, which Sanders blames for shifting the balance of electoral power to "billionaire families now able to spend hundreds and hundreds of millions of dollars to purchase the candidates of their choice."
Sanders is betting his popularity with liberal activists — and their willingness to take him on as the closest thing to Warren, who is not running — could goose a campaign that will come out of the gates with only about 6% support in the most recent polls. The self-described independent socialist has a strong following online and will fundraise aggressively across the grassroots progressive community.
"He knows how to do the organizing that's required," Tad Devine, a Democratic strategist and likely bet to lead Sanders' campaign, told the Washington Post last fall. "As a mass media person, I also think he would be a great television candidate. He can connect on that level."
Against the odds: "I realize I'm not a household name," Sanders told the Charlotte Observer in August 2014, but "I think the average American is a lot more frustrated with the establishment than a lot of people perceive. I think there's receptivity for voices that are going to speak for a working class that is being battered."
Sanders is going to give those voters all the liberal red meat they can eat. But more importantly for Democrats, his arrival means Clinton will have no choice but to sink her teeth in too.