With a mix of relatively strong and relatively weak polls for each of the major candidates, the top line of our 2020 Democratic primary forecast has been roughly unchanged over the past several days.
In a race without a clear favorite, former Vice President Joe Biden remains the front-runner, with a 39 percent chance of winning a majority of pledged delegates. He’s followed by Sen. Bernie Sanders with a 23 percent chance, Sen. Elizabeth Warren with a 13 percent chance and former South Bend, Indiana, Mayor Pete Buttigieg with a 10 percent chance. The chance that no one will win a majority of pledged delegates is 14 percent. All of those figures are within 1 percentage point of when I last wrote about the forecast on Saturday.
The twist, though, is that this time Biden’s strongest new polls — at least, in terms of how much they helped or hurt him in the model — were in Iowa and New Hampshire, whereas he got middling numbers in new polls of Nevada and California (along with a not-particularly-great set of national numbers).
In a Monmouth University poll of Iowa released on Monday, Biden led the pack with 24 percent of the vote, followed by 18 percent for Sanders, 17 percent for Buttigieg and 15 percent for Warren. Meanwhile, an RKM Research and Communications poll of New Hampshire, conducted for Franklin Pierce University and the Boston Herald, had Biden ahead with 26 percent of the vote there, leading Sanders at 22, Warren at 18 and Buttigieg at 7.
None of that puts Biden in a spectacular position. But the conventional wisdom (at least as espoused by prediction markets) seems to assume that Sanders is considerably more likely than Biden to win in Iowa and New Hampshire. That isn’t really true based on the polls in each state, however. Of the three most recent Iowa polls, for instance, Biden was tied for the lead in one and led outright in another, the same as Sanders. Our model essentially regards Biden and Sanders as co-favorites in each of the first two states, with Warren and Buttigieg also having decent chances.
And if Biden does win the first two states, he’d be in a very strong position, with a 92 percent chance of winning a majority of pledged delegates and a 95 percent chance of winning a plurality.1 On average in such scenarios, Biden would win 2,747 of the possible 3,979 pledged delegates and 50 of the 57 nominating contests.
So as much as we like to emphasize the uncertainty in the outlook, scenarios that involve Biden winning do come up more often than those for other candidates. And some of those scenarios involve Biden winning the nomination easily.
Others could involve a split outcome in the first two states. What if Biden wins either Iowa or New Hampshire but not both? He’d be the favorite overall, but that could lead to a reasonably close race. If he won Iowa but lost New Hampshire, Biden would have a 56 percent chance of a pledged delegate majority and a 67 percent chance of a plurality. The reverse scenario — where Biden loses Iowa but wins New Hampshire — would be slightly better for him, giving him a 66 percent chance of a majority and a 76 percent chance of a plurality.
Make sure to check out FiveThirtyEight’s Democratic primary forecast in full; you can also see all the 2020 primary polls we’ve collected, including national polls, Iowa polls, New Hampshire polls, Nevada polls and South Carolina polls.