Fun fact: There are 174 people running for the Democratic nomination for president. You likely know Hillary Clinton and Bernie Sanders — they’ve gotten almost all the media attention. But tonight’s Democratic debate (which we’ll be live blogging beginning short after 8 p.m. EDT) will also feature three of the 172 others: Lincoln Chafee, Martin O’Malley and Jim Webb. So, without further ado, let me introduce you to the Democratic also-rans, what they’ve been up to and why their candidacies haven’t taken off.

Martin O’Malley — former governor of Maryland

O’Malley is the only life-long Democrat in the Democratic field. He was a two-term governor and notched several progressive achievements, including passing legislation legalizing same-sex marriage and outlawing the death penalty in Maryland. All he has to show for it are the anemic poll numbers above.

Still, O’Malley is a plausible candidate — he’s just been squeezed out so far. Clinton has racked up most of the endorsements from the Democratic mainstream, and Sanders has claimed the liberal alternative lane. O’Malley could try to push aside Sanders, but his record on policing as mayor of Baltimore and his past chairmanship of the moderate Democratic Leadership Council have hurt him in his appeals to liberal voters.

It’s a long shot, but O’Malley’s better bet is probably to position himself as the mainstream alternative to Clinton, especially if Joe Biden doesn’t run. If you’re looking for the candidate who can most benefit from the debate, O’Malley is the one. Of the three also-rans presented here, he is the only one who can claim a strong connection to Democratic powerbrokers and point to liberal achievements he made while in office.

Lincoln Chafee — former governor and senator from Rhode Island

National: 0.6 percent

Iowa: 0.5 percent

New Hampshire: 1.0 percent

Chafee is one of two Democratic candidates in the 2016 field never to win an election as a Democrat (Sanders is the other). Chafee was a Republican senator, then an independent governor, then became a Democrat while in office.

The biggest news Chafee’s campaign has made since it launched in early June came in his announcement speech, when he called for moving the United States to the metric system. He continues to talk about Clinton’s vote for the Iraq War, but most Democrats don’t care about that much anymore. Even if they did care, Sanders also voted against the Iraq War.

When combining campaign and PAC money through July 31, Chafee raised the least amount of money of any of the major candidates running for either party’s nomination.

He’s unlikely to make much more noise during this campaign. Still, at least the metric system has a champion.

Jim Webb — former senator from Virginia

National: 1.2 percent

Iowa: 1.2 percent

New Hampshire: 1.0 percent

Webb is a candidate who’s out of time. He’s conservative for a Democrat — a former Reagan administration official whose position on the confederate flag has been mixed. He does have a niche, appealing mostly to white moderates.

Webb’s problem: The Democratic Party has become increasingly liberal and increasingly non-white. The percentage of non-whites has doubled over the last 25 years, while the percentage of liberals has risen by 14 percentage points over the last 15.

Webb’s best chance will come when the Democratic race moves away from the early states and into areas with more moderate and conservative white voters, such as Appalachia and the South. Perhaps he can use the debate to build strength among these shrinking Democratic constituencies.

The debate isn’t likely to make or break Chafee or Webb — neither has a strong base within the Democratic primary electorate. For O’Malley, however, it’s time to shine or risk continuing to shrink into the shadows.

Check our our live coverage of the first Democratic Debate.