(CNN) The endorsements keep on coming for former Vice President Joe Biden. On Monday, California Rep. Tony Cárdenas backed Biden's bid to be the Democratic nominee for president. It was Biden's 32nd endorsement from a governor or sitting member of Congress. No other Democrat has more than 13.

Biden's lead in endorsements is good news for him because candidates who lead in endorsements at this point usually do well in the primary. It paints the picture of a front-runner who may not be strong, though certainly is not weak, either.

Since 1980, there have been 14 primaries without an incumbent running in a given party's primary. For each of those, I looked at a dataset of endorsements in which each governor's endorsement was given 10 points, each senator's endorsement was given 5 points and each House member's endorsement was given 1 point.

The candidate leading in the endorsement primary at this point won 10 out of 14, or 71% of the time using this methodology. The only candidates who were winning the endorsement primary at this point and didn't go on to be the nominee were Democrat Dick Gephardt in 1988, Democrat Howard Dean in 2004, Democrat Hillary Clinton in 2008 and Republican Jeb Bush in 2016.

Biden, though, has something else going for him: he's also leading the polls. Gephardt in 1988 and Bush in 2016 were not anywhere near the lead in the national polls at this point. When candidates are leading in endorsements and the polls, they have won 7 out of 9 times (78%). When they lead in just endorsements and not the polling, they're 3 out of 5 (60%).

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