The main draw in Tuesday's first 2016 Democratic presidential debate is undoubtedly Hillary Rodham Clinton, the once untouchable Democratic front-runner, vs. Sen. Bernie Sanders, the independent socialist senator from Vermont who is giving her a run for her money.

But there are actually three other guys who will be on the stage with the Clinton and Sanders. It's okay if you haven't heard of them: None crack even 1 percent in an averaging of national primary polls so far. But since they all have a lot to prove -- like proving you will know and remember who they are come Wednesday morning -- these guys could be throwing some of the night's biggest punches.

Here's your cheat sheet to the three underdogs in the Democratic debate (in alphabetical order by last name):

Name: Lincoln Chafee

Resume: Independent-turned-Democratic governor of Rhode Island from 2011-2015

Republican senator from Rhode Island, 1999-2007 (Chafee was appointed to the seat after his father died and then won a six-year term before losing another)

Best known for: Evolving from a Republican to an independent to a Democrat. After Chafee lost his Senate reelection in 2006, he became an independent and ran for governor in 2010. He won, but facing poor poll numbers, he switched to the Democratic Party in 2013. He decided not to run for a second term, in large part because he pretty clearly would have lost.

[A brief history of Lincoln Chafee's party identity crisis]

Standout political stance: Chafee was the only Republican senator who voted in 2002 against authorizing the use of force in Iraq, and he frequently criticized President George W. Bush's foreign policy. Opposing the Iraq war is at the core of his presidential campaign today. "I don't think anybody should be president of the United States that made that mistake" of voting for the Iraq war, Chafee told The Post in April. Chafee also wants to forgive Edward Snowden and let him return home.

Standing in the polls: Chafee has struggled to gain any attention at all. He'd get 0.3 percent of the vote if a national Democratic primary were held today, according to a RealClearPolitics average of recent polls.

Go-to lines: "America loves an underdog."

Interesting fact: Chafee wants the United States to convert to the metric system. In fact, he mentioned it in his brief June presidential announcement, arguing the symbolic move would help America "reengage with the international community."

Name: Martin O'Malley

Resume: Governor of Maryland, 2007-2015

Mayor of Baltimore, 1999-2007

Best known for: While governor, O'Malley shepherded and signed a gun-control package into law. He also presided over Maryland legalizing same-sex marriage and abolishing the death penalty. 

Standout political stance: O'Malley is one of the strictest in the field when it comes to gun control; he wants to ban assault weapons, require that every person who buys a gun acquire a license and get fingerprinted, make gun trafficking a federal crime and use executive action to have the federal government buy guns only from companies that employ strict safety technology. 

Standing in the polls: O'Malley was seen as perhaps the liberal alternative to Clinton, but he got into the race in late spring as Sanders was already picking up momentum. He's failed to find his own; according to a new Washington Post-University of Maryland poll, he gets just 4 percent of support from Democrats and Democratic-leaning voters in his home state (where he didn't exactly end his tenure as governor on a high note).


Nationally, O'Malley is doing even worse: He would get 0.4 percent of the vote if the primary were held today, according to RealClearPolitics's average.

Go-to lines: Unlike the top two candidates, O'Malley hasn't backed down from attacking others in the race. He says that Sanders is "a protest candidate" and that people of Iowa had their say on Clinton when she finished third there in 2008.

He also pitches himself as the real progressive in the race: “I am the only candidate in this race who can stand before you with 15 years of executive experience."

Interesting fact: O'Malley is the founder and lead singer of the Celtic rock band O'Malley's March, which he put together in his 20s. Strumming on his guitar at campaign stops is a favorite activity of his. He also has been known for taking off his shirt.

Name: Jim Webb

Resume: Senator from Virginia, 2007-2013

Navy secretary under President Ronald Reagan, 1987-1988

Assistant secretary of defense for reserve affairs under Reagan, 1984-1987

Decorated Marine and New York Times bestselling author

Best known for: Championing prison reform in the Senate as far back as 2008 -- specifically reducing sentences for nonviolent drug offenders, parole violators and the mentally ill.

Standout political stance: Webb is a former Republican who is one of the most conservative Democrats in the race. He supports gun rights and opposes cap-and-trade policies and coal plant regulations. In the late 1970s, he also quite vocally opposed allowing women into combat.

But Webb's views aren't all center-right. He's an economic populist who wants to cut CEO pay. He was also ardently opposed to the Iraq war -- before many other Democrats were, he likes to remind everyone.

Standing in the polls: After months of genuine indecision, Webb launched his campaign in July with a ripple. He'd get 0.9 percent of the vote if the Democratic primary were today, according to RealClearPolitics.

Go-to lines: "I understand the odds, particularly in today’s political climate where fair debate is so often drowned out by huge sums of money. Let’s clean out the manure-filled stables of a political system that has become characterized by greed.”

Interesting fact: Webb once coldly brushed off Bush when the president asked Webb how his son, who was serving in Iraq at the time, was doing.

“That’s between me and my boy, Mr. President," he said.