Back in August, we noted that Democrats might be slow to endorse in the 2020 presidential primary because of the uncertainty surrounding its historically large candidate field. And so far, that’s exactly what’s happened — Democratic officeholders have now endorsed at about the same rate as their slow-moving Republican counterparts in 2016.

Endorsements have historically been a predictive indicator of who will win their party’s nomination, which bolsters the theory that “The Party Decides,” but Democratic leaders may be choosing not to decide in 2020. Nonetheless, among those who have endorsed, former Vice President Joe Biden holds a clear lead.

As of Friday, only 104 of 303 Democratic governors, senators and representatives have endorsed a candidate. At this point in the 2016 election cycle, slightly more Republicans had endorsed a candidate (117), though there were a few more Republicans in Congress and governors mansions then (333) than there are Democrats in those positions now (303). Still, 35 percent of possible GOP endorsers had backed someone in 2016, which is practically the same as the 34 percent of Democrats who’ve endorsed someone in 2020.

Democrats started the 2020 cycle endorsing at a faster clip than 2016 Republicans, but their rate has slowed since March (about 600 days before the general election). In the last presidential election, 60 Republicans had endorsed someone between mid-August 2015 and the first weeks of 2016 — to be specific, between 450 and 300 days before the election, which is equivalent to the period from when we published our previous analysis of the endorsement rate last August to about now — but only 29 Democrats have done so during the same time span this cycle. However, Hans Noel, a political scientist at Georgetown University and a coauthor of “The Party Decides,” told me we shouldn’t over-emphasize the pace of endorsements as compared to the overall volume and who’s getting them. “There are some years when no one gets involved very quickly at all,” said Noel. “There’ve been some years when elites got involved after Iowa. Once they found out what happened in Iowa, they jumped in.”

And although the rate of endorsements has slowed, most of the ones made in recent weeks have gone to Biden. He now has 35 from Democratic governors and members of Congress, and has received seven of the eight endorsements made since Dec. 1, including some from junior House Democrats in competitive seats (former South Bend, Indiana, Mayor Pete Buttigieg received the other one).

The sort of geographical and racial diversity we see among Biden’s endorsers has historically been an indication of broader acceptance by party members and a precursor of success in nomination contests, according to the authors of the “The Party Decides.” And if you look at support outside a candidate’s home state, Biden’s geographical lead is readily apparent. Overall, 89 percent of Biden’s backers come from outside Delaware, which admittedly is a small state. The next-closest contenders behind Biden are Sens. Elizabeth Warren and Cory Booker, who each have 12 endorsers apiece, but only half of Warren’s hail from somewhere other than Massachusetts and none of Booker’s are from outside New Jersey. And with Sen. Kamala Harris now out of the running, Biden easily has the most racially diverse set of endorsers, too, including nine members of the Congressional Black Caucus and five from the Congressional Hispanic Caucus.

Still, Biden doesn’t dominate among all Democratic officeholders with endorsements to give. If we look at more left-leaning Democrats — those who belong to the Congressional Progressive Caucus, the most influential liberal ideological caucus in Congress — Warren leads the way with 11 endorsements, Biden is in second with six and Sen. Bernie Sanders in third with five. University of Maryland political scientist David Karol, another coauthor of “The Party Decides,” believes Biden still has work to do with winning over more liberal members of his party. “Biden has more breadth of support than other people running, when it comes to race and region,” Karol said. “But he has not done as well with progressives, particularly white progressives.”

Biden may still lead handily in the endorsement primary for now, but it’s important to remember that most potential Democratic endorsers (66 percent) are still sitting on the sidelines. What’s more, there are actually quite a few endorsers this cycle who endorsed a candidate who has since dropped out and have yet to throw their support behind another candidate. Of the 104 Democrats who’ve endorsed someone, 27 have backed a candidate who is no longer running and have yet to switch to a new contender. Of those endorsers, 17 supported Harris, who dropped out in December. By contrast, in the 2016 cycle, only four of 117 Republican endorsers had backed GOP contenders who had dropped out by this point.

Harris’s exit is especially interesting in that she had more endorsements than anyone save Biden, yet she dropped out anyway, suggesting that endorsements weren’t enough to save her flagging campaign. (Unlike Biden, who is at 28 percent in the national polls, Harris struggled to climb past 5 percent in recent months.) As for why more of Harris’s backers haven’t thrown their weight behind another candidate (maybe Biden?), Karol said that these endorsers had “bet on the wrong horse, so they may be a little gun-shy after missing the first time around.” More broadly speaking, though, part of the reason Democratic leaders may be hesitant to endorse anyone in 2020 is because they were so quick to back Hillary Clinton in 2016, who went on to lose the general after a bitter primary, in which the party establishment was accused of putting its thumb on the scale for her.

But also, when there’s a lack of clear consensus, as there has been here in 2020, many party leaders wait to make a choice so that a primary can be more open. “If they aren’t very committed [to a candidate], they don’t create a sense that people need to support someone or direct their resources to that candidate,” said Noel. He added that, “If there’s lukewarm support from party leaders, that could create an opening for someone else.” Biden’s opponents in the Democratic race will certainly hope that’s the case, and the fact that most Democrats haven’t endorsed someone yet might leave the door ajar.