We tallied up all the votes the 2020 Democratic contenders have ever won on their own, and Joe Biden is near the bottom

• Using historical election results, INSIDER calculated how many votes each candidate has accrued over their lifetimes.
• Our research shows that candidates who earned the most votes - including Harris, Sanders, and Gillibrand - did so in very different ways.
• Harris drew most of her votes from state-wide contests in California, whereas Sanders drew the majority of his total from the 2016 Democratic primary.
• Depending on how you count votes cast in general presidential elections, Biden is either the runaway winner in total votes or somewhere near the middle of the pack.
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Twenty candidates for the Democratic nomination descended on Miami this week for the first round of the party's debate process. Each qualified for the event by accruing more than 130,000 donors or clearing at least two percent in polls approved by the Democratic National Committee. Four candidates in the race - Steve Bullock, Mike Gravel, Wayne Messam, and Seth Moulton - failed to do so.

The trouble with this criteria is that donations and polls offer a limited window into a candidate's future chances. This is because elections are not about accumulating capital or persuading supporters to reveal their preference to a pollster. Elections are about getting people to vote.

With this in mind, INSIDER compiled historical election results for every candidate in the 2020 Democratic primary. Relying on data compiled by Our Campaigns, a collaboratively-edited election database established in 2002, we tallied the number of votes that each of the 24 candidates collected over their lifetimes, in both primary and general elections, regardless of whether they won or lost.

The result, seen below, is something of a longitudinal portrait of each candidate's ability to draw votes. Keep reading, and you'll find our analysis of the data and what it means for the 2020 election.

The frontrunners

• At least three candidates - Kamala Harris, Bernie Sanders, and Kirsten Gillibrand - have collected more than 10 million votes each.
• Harris garnered the bulk of her votes in a sequence of general elections in California, the most populous state in the union. She also benefited from Proposition 14, a California ballot measure passed in 2010 that ended party-based primaries in favor of open ones. Harris drew more than 5 million votes from open primaries alone.
• Most of Sanders' votes came from the 2016 Democratic primary, during which he collected more than 13 million ballots in contests held in all 50 states. The remainder came from a long string of elections in Vermont, the second-least populous state, dating back to his 1971 run for U.S. Senate as a member of Vermont's Liberty Union Party.
• Nearly all of the votes for Gillibrand were cast in general elections for her seat in the U.S. Senate, where she represents New York, the third-most populous state. She previously served in the House, representing Albany and surrounding areas upstate, and was appointed by former New York governor David Paterson to replace Hillary Clinton when she resigned her Senate seat in 2009 to serve as Secretary of State. She won subsequent elections for the same seat in 2010, 2012, and 2018.

The trouble with Biden

• The electoral history of Joe Biden is difficult to compare with the other candidates, mainly due to how presidential elections work. 
• If you count votes cast in general presidential elections, Biden received more than 135 million votes. If you don't count those votes, his lifetime total drops to approximately 846,000 votes, mostly drawn from his career in the U.S. Senate, where he represented Delaware, the sixth-least populous state. We've designed the chart so you can toggle between the two calculations.
• There are methodological reasons to treat general presidential elections differently. Every other race in our data set occurred at the state or city level and featured candidates who ran by themselves. The general presidential election, by contrast, is a national and therefore much larger contest in which presidential candidates - not voters - select running mates to serve as Vice President. In 2008 and 2012, one of those candidates was Barack Obama, who chose Biden.
• In other words, a tremendous amount of people cast indirect votes for Vice President. Calculating Biden's electoral history depends, then, on whether votes cast for Obama ought to count for Biden, too.

The rest of the field

• Three candidates - Inslee, Klobuchar, and O'Rourke - collected between 5 and 10 million votes.
• Eight candidates - Warren, Delaney, Bennet, Ryan, de Blasio, Hickenlooper, Booker, and Castro - collected between 1 and 5 million votes.
• The remaining candidates - Tulsi Gabbard, Eric Swalwell, Steve Bullock, Pete Buttigieg, Mike Gravel, Marianne  Williamson, and Wayne Messam - earned somewhere south of 1 million votes.
• Just one candidate, Yang, has never run for office and therefore has never earned a vote in a primary or general election.

What the data mean

As we noted above, the top four vote-getting candidates - Harris, Sanders, Gillibrand, and possibly Biden - earned their votes in very different ways. Harris gained most of her total from state-wide contests in California; Sanders from the 2016 Democratic primary; Gillibrand from three consecutive races for the U.S. Senate in New York; and Biden from the general presidential elections in 2008 and 2012.

On their face, these numbers suggest Harris is the Democratic Party's most viable option for defeating Donald Trump in the general election in 2020. As of today, Americans have cast more votes for her, and for her alone, than any other competitor.

The same numbers also suggest, perhaps counterintuitively, that Sanders is the most formidable challenger in the current Democratic primary. After all, Harris has posted more total votes than Sanders, but Sanders has posted more primary votes than Harris - or any other candidate.

Of course, these suggestions rest on a crucial assumption: That the cumulative total of votes cast for a particular candidate, in a particular kind of election, is predictive of future elections in which that candidate runs. While there is something intuitive about this assumption, we were unable to find academic research that formally tested it. Doing so would likely require collecting and tabulating data from thousands of races, and figuring out the fairest way of comparing them.

Even if you reject that assumption, however, the data remain illustrative. The electoral history of Warren and Buttigieg, in particular, do not correspond to the intensity of attention and fundraising they have attracted. This could mean they are running uncommonly strong campaigns. It could also mean that attention and fundraising aren't necessarily the best way to forecast the outcome of an election. 

It's worth remembering, finally, how many votes the current President of the United States had earned when he announced his candidacy more than four years ago: 23,179.

Maybe Williamson and Yang are the true front-runners after all.