Our 2020 primary model looks at the race sequentially: When a primary or caucus is complete, the model will try to anticipate whose support will rise or fall based on the result. Even before the mess in Iowa, though, where both Pete Buttigieg and Sen. Bernie Sanders have claimed victory, we advised readers to interpret these projections provisionally — the model estimates how a contest will affect each candidate’s chances but will update those estimates once new polls come out.
So how are the model’s post-Iowa estimates looking now that we’ve gotten a few new polls since Iowa? Pretty good, actually. Let’s run through the latest surveys and what they mean.
Most of the new polls we’ve gotten have come in New Hampshire, which votes on Tuesday. There, Buttigieg has gotten a bit of a bounce; the former South Bend, Indiana, mayor’s chances of winning the Granite State are up to 1 in 5, from about 1 in 8 before Iowa. A new Monmouth University survey of New Hampshire conducted Feb. 3-5 found Sanders leading with 24 percent and Buttigieg in second with 20 percent. Two tracking polls in New Hampshire from Emerson College and Boston Globe/Suffolk University out Wednesday also found Buttigieg in second to Sanders.
Those polls also seemed to confirm the bad news for Biden, as his fourth-place showing in Iowa has really hurt his standing in our forecast. The two tracking polls in New Hampshire both put him at 12 percent, well behind Sanders and Buttigieg.1 Meanwhile, a series of national polls from Morning Consult measuring preferences each day between Feb. 3 and Feb. 5, showed Biden’s standing in falling from 29 percent to 24 percent. This was largely in line with what the model anticipated2 but still hardly qualifies as great news for him.
How representative New Hampshire will be for the race overall is still an open question — it just happens to be where we have the freshest data. Perhaps the Morning Consult polls suggest that Biden’s post-Iowa support will be more durable nationally, and in more diverse states, than in a mostly white state like New Hampshire. Or maybe more national polling will show a more drastic decline.
Buttigieg has the reverse problem (or opportunity): The New Hampshire polls show him gaining ground after his Iowa performance, but his chances of winning a majority of pledged delegates overall haven’t improved much. Morning Consult’s polling showed him gaining ground, from 7 percent to 12 percent. But 12 percent isn’t good for much. A YouGov poll released Wednesday had him at just 9 percent — not much changed from previous YouGov surveys. Buttigieg will need to expand his coalition, including to non-white voters, to stand much of a chance in contests beyond Iowa and New Hampshire.
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So let’s get back to the model. Our forecast now gives Sanders about a 1 in 2 chance of winning a majority of pledged delegates. The second likeliest outcome (1 in 4 chance) is that no candidate wins a majority. After that, the next-strongest candidate is former Vice President Joe Biden, who has roughly a 1 in 5 shot (20 percent). No other candidate is currently above 5 percent, including Sen. Elizabeth Warren and Buttigieg, the former mayor of South Bend, Indiana (5 percent and 3 percent, respectively).

But much of the movement in the model over the past 24 hours — including further gains for Sanders — has actually come from inputting the shifting results from Iowa, which have been trickling in from the state Democratic Party. For instance, when we restarted the model on Wednesday with partial Iowa results, Sanders’s chances of winning a delegate majority rose from 31 percent to 39 percent. Biden’s chances fell from 43 percent to 19 percent. And Warren’s and Buttigieg’s chances went up, from 5 percent to 9 percent and 4 percent to 6 percent, respectively.
Then another vote update in the wee hours of Thursday morning moved Sanders into a near-tie with Buttigieg for the Iowa lead in state delegate equivalents (Sanders already led the first and final preference vote counts). In turn, our model gave Sanders more of an Iowa bounce (and Buttigieg less of one), raising Sanders from a roughly 2 in 5 chance to about a 1 in 2 shot of winning a majority of pledged delegates.
Truth be told, we still don’t have that much post-Iowa polling, so the forecast could definitely shift in the coming days if fresh surveys show more gains or losses for these leading candidates. For now, though, the Iowa results have made Sanders the front-runner to win the Democratic nomination, and the new polls we have generally agree. Though maybe the true headline coming out of Iowa is simply how wide-open and uncertain the race is: No single candidate has better than a 50 percent shot to win a pledged-delegate majority, and there’s a 1 in 4 chance that we get through all the primaries and caucuses without anyone getting there.