2020 Democratic presidential candidates. (Reuters) (Reuters File Photo/Reuters)

One thing that tends to be obscured in the world of politics is that even the most successful politicians don’t really have that much experience in electoral politics.

Sure, you’ve got outliers such as former Michigan congressman John Dingell who won 31 straight House elections in a row. But most politicians have a record more like that of former president Barack Obama, who won three state Senate races, lost a House race, won a U.S. Senate race and then won the presidency twice. That’s a total of seven elections for one of the most successful Democrats in modern U.S. history.

The effects of this on the campaigns themselves are not small: Incumbent candidates often think that they have figured out the magic of winning elections, regardless of how fluky that win might have been. Campaign managers are often unhappy to hear sentences that begin with some version of “well, last time we …”

Those short histories also mean that phrases such as “never lost a race” lose some meaning. As do claims about how often a candidate has faced the voters. A 40-year career in the Senate, for example, could mean six elections — many of them won by lopsided margins thanks to the advantages of incumbency.

If you’re wondering: Yes, I am passive-aggressively responding to things people have said about the 2020 Democratic primary field.

There are several politicians running for the Democratic nomination who have good political track records. Historically, candidates who win races are more likely to get nominations, because the public is more likely to be aware of them. But it’s worth walking through just how many victories those candidates have won and, as important, how close the wins were.

Visually, here’s the electoral history of the 2020 Democratic candidates who are polling the best. All columns represent margins in individual elections. It considers only nonprimary campaigns and elections for seats at the mayoral level or higher.

(Philip Bump/The Washington Post)

The summary?

Former vice president Joe Biden has won nine of nine races, seven Senate and two as Obama’s vice president. He won his Senate races by an average of 29 points and only once, in his first race, won by less than 5 points. He represented Delaware, a blue state.

Sen. Cory Booker (D-N.J.) has won four of five races, losing one of three mayoral bids and winning two Senate races. He won those Senate races by an average of 12 points in New Jersey, a blue state. None of the races he won was closer than 10 points.

South Bend, Ind., Mayor Pete Buttigieg has won two of three races, losing his bid to be Indiana’s state treasurer in 2010. (Fun fact: He lost to the incumbent, Richard Mourdock, who went on to have one of the more spectacular recent political flame-outs in his 2012 Senate bid.) Buttigieg easily won election as mayor of South Bend twice. The city is Democratic; the state isn’t.

Sen. Kamala D. Harris (D-Calif.) is three for three, winning two state attorney general races, one by less than a point and the other, her reelection, by 15. She won election to the Senate over another Democrat by 23 points in California, a blue state.

Sen. Amy Klobuchar (D-Minn.) is three for three in Senate races, averaging a 26-point win margin. She represents Minnesota, a purplish blue state.

Former congressman Beto O’Rourke (D-Tex.) is three for four, winning three House races in his Democratic district by an average of 49 points but losing last year’s Senate race in Texas by about three points.

Sen. Bernie Sanders (I-Vt.) has run more races than has any of the other candidates, racking up 15 wins in 16 races in dark-blue Vermont. (His one loss was a gubernatorial bid in 1986.) He won his House races by an average of 28 points and his Senate races by an average of 40. Only twice has he faced a close race, edging out his Republican House opponent by three points in 1994 and barely winning his first mayoral race in Burlington, Vt., by 10 votes. (In each of his mayoral races, he defeated Democrats.)

Sen. Elizabeth Warren (D-Mass.) has twice run for the Senate in blue Massachusetts, winning by an average of 16 points.

In total, that’s 41 wins in 45 tries by eight candidates, with only five races that were within five points. This covers 145 collective years in electoral politics.

So has Biden been pored over by voters for the past 50 years? Well, if you count his vice-presidential bids as including significant scrutiny of his record and if you include his landslide Senate wins from 1978 to 2002 as reflecting a thoughtful rejection of his Republican opponents, sure. Does Warren’s perfect record tell us something about her electoral abilities? I guess, if you think a Democrat winning two races in Massachusetts implies a near-invulnerability.

It’s very easy to sit back and say “nothing is predictive.” It’s also not entirely true; having won elections in the past does at least show that a candidate has some sense of how to connect with voters successfully. But as the Democratic contest is increasingly focused on “electability,” it’s worth being a bit skeptical about those claims which are based on the candidate’s past successes.