Obviously, everyone knows about Hillary Clinton. The former Secretary of State under President Obama, eight-year Senator from New York, and First Lady to President Bill Clinton, has been in the national spotlight for nearly three decades, and we know about everything from her policy positions to her personal life. In recent months, Bernie Sanders, the independent democratic-socialist form Vermont, has also become well known. He’s drawn huge crowds, and although his winning the Democratic nomination remains a long shot, he’s become a legitimate rival to Hillary Clinton.

But there will be three other candidates on stage tonight: former Maryland Governor Martin O’Malley; former Virginia Senator Jim Webb; and former Rhode Island Senator Lincoln Chafee. You’d be forgiven for not knowing too much about these three. Their candidacies have failed to gain much traction, and the Real Clear Politics poll average places each of them at or below 1% nationally. Still, they’ll be up there tonight with Hillary and Bernie, so here is a bit of background on each of them.

Jim Webb

Webb, formerly a Senator from Virginia before declining to run for reelection in 2012, is a Vietnam veteran and actually first entered politics under a Republican president, Ronald Reagan, serving as Secretary of the Navy late in Reagan’s second term. In 2006, he was elected Senator in Virginia, running largely on a platform of moderate positions and opposition to the Iraq War. He defeated incumbent George Allen in an election that became a national spectacle after Allen used an obscure racial slur at a campaign rally.

There was some speculation that Webb would be a potential running mate for Obama in 2008, due to his moderate appeal and international affairs background. Webb’s campaign website puts him squarely on the left on the issue of economic inequality, claiming that today’s economic environment is great for people who own stock, but bad for workers.

Martin O’Malley

O’Malley is perhaps most famous for playing guitar in a Celtic rock band, and he was recently endorsed by Dropkick Murphys, one of the genre’s biggest bands. Rock career aside, though, O’Malley served as Mayor of Baltimore before winning two terms as the Governor of Maryland. He is fairly progressive, emphasizing his commitment to taking down too-big-to-fail Wall Street institutions on his website.

He also is committed to using data to support policy positions, reports the Washington Post. O’Malley has progressive credentials on a number of other left-wing issues, including gun control, the death penalty, and same-sex marriage.
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Lincoln Chafee

Chafee is perhaps the strangest entry onto this list. While Webb was appointed to a position by a Republican president, Chafee actually was a Republican Senator, serving just more than one term from Rhode Island (he finished his father John’s term after his death), and then won another term the next year before losing his reelection bid in 2006. Chafee is consistently ranked as one of the most liberal Republicans in the Senate, and after he lost his reelection he became an independent, and then a Democrat.

Chafee is running largely as a pro-peace candidate, emphasizing his vote against the Iraq War. He also stresses that he wants to eliminate tax loopholes for wealthy corporations, and that he wants to raise the minimum wage.