Primaries are a lot harder to predict (and poll) than general elections, in large part because partisanship is taken out of the equation. So in addition to looking at horse-race polls of the 2020 Democratic presidential primary, paying attention to which candidates are viewed favorably and unfavorably — and which have yet to make an impression — can tell you a lot about the direction of the race, even at this early juncture. I last wrote about favorability polls of the 2020 candidates all the way back in February, so it’s high time we checked in on how these numbers have changed.

Historically speaking, nonincumbent presidential nominees tend to be candidates who are already well-known and well-liked within their party early in the campaign or candidates who are not yet very well-known. However, maybe that’s just because most presidential candidates, period, tend to be one of those two things (as opposed to well-known and disliked). Certainly, most 2020 Democratic candidates are, based on an average of national polls of Democrats and Democratic leaners conducted entirely in the month of May.

For example, seven major candidates, led by former Vice President Joe Biden, have net favorability ratings (favorable rating minus unfavorable rating) above +30 percentage points, and the share of Democrats who can form an opinion of them (favorable rating plus unfavorable rating) is above 55 percent. Meanwhile, 11 major candidates are relatively unknown (fewer than 40 percent of Democrats have an opinion of them). Note that, almost by definition, these candidates do not have very high net favorability ratings (the highest is +12). This is because people have to know who a candidate is to like her, so a candidate’s net favorability rating can never exceed the share of Democrats with an opinion of her.

This leads to a strong relationship between a candidate’s net favorability rating and the share of voters who can form an opinion of her, represented by the trend line in the chart below. However, some Democratic hopefuls are more popular than the share of Democrats with an opinion of them would indicate (i.e., their dots are located above the line in the chart), while others are less popular (i.e., their dots are located below the line). For example, based on the 62 percent of Democrats with an opinion of Sen. Cory Booker, we’d expect him to have a net favorability rating of +33 points. His actual net favorability rating is +36 — so Booker is slightly more popular than expected (and his dot is located above the trend line). New York City Mayor Bill de Blasio is, to put it politely, in a different position.

Forty-six percent of Democrats knew enough about de Blasio to form an opinion of him, but his net favorability rating is -1 when it “should” be around +20. Yes, that means more members of de Blasio’s own party dislike him than like him. That’s a huge handicap to de Blasio’s chances of winning the nomination.

After de Blasio, Reps. Tulsi Gabbard and Tim Ryan are the farthest below the trend line, indicating that they are unexpectedly unpopular. Only about a third of Democrats are familiar with them, and their net favorability ratings are lower than they “should” be by 9 points and 6 points, respectively, based on the statistical relationship between the two. The news is better for Sen. Kamala Harris and Washington Gov. Jay Inslee: They are beating expectations by the widest margins. Both have net favorability ratings that are 6 points higher than the share of Democrats with an opinion of them would predict.

For heavily polled candidates, we can also compare their favorability ratings in the May polls to what they were in January and February, the last time we did this analysis. Doing so reveals that over the past few months, all 12 such candidates became better-known (although some saw bigger increases than others). But at the same time, some candidates grew more popular, while others became less popular.

As you can see in the chart above, Pete Buttigieg has made the biggest jump in the polls — by far. The share of Democrats with an opinion of him rose by 36 points, and his net favorability rating rose by 27. Three other candidates who significantly increased the share of voters with an opinion of them are Sen. Amy Klobuchar (whose share of voters with an opinion of her increased by 15 points), Rep. Beto O’Rourke (+14) and Harris (+11), but none saw an equivalent change in their net favorability ratings. Klobuchar’s and Harris’s increased by 7 and 6 points, respectively, while O’Rourke’s barely changed at all. In fact, he went from being more popular than you’d expect to slightly less popular.

The candidate with the biggest change in net favorability rating since February is Biden — but it was in the wrong direction: His net favorability rating dropped 10 points. This could be a result of the allegations from women who said Biden touched them inappropriately, which were widely covered in the weeks before his campaign announcement on April 25.

It may also be that Biden’s old net favorability rating was unsustainably high and he was due for a course correction. In my February article, Biden’s net favorability rating (+69) was 12 points higher than his name recognition would have predicted (+57) — making him a significant outlier among the candidates whose ratings we examined. When the 10-point drop came, he was well-positioned to absorb the hit; his net favorability rating is now much closer to what it “should” be (although it’s still a little better than expected). That certainly hasn’t diminished his standing in the horse race: The former vice president has seen a significant jump in his support since throwing his hat in the ring.

Finally, the favorability ratings of the other seven candidates in the chart didn’t change too much — not exactly a great sign after several months of campaigning. For example, the share of Democrats with an opinion of Rep. John Delaney increased only 2 points, and his net favorability rating rose by 1 point. Already one of the least-known candidates in the field, Delaney doesn’t appear to be making much headway with his campaign.

Derek Shan contributed research.

Check out all the polls we’ve been collecting ahead of the 2020 elections.