Joe Biden is the most likely person to win a majority of pledged Democratic delegates, according to the FiveThirtyEight primary model, which we launched on Thursday morning. This is our first-ever full-fledged model of the primaries and we’re pretty excited about it — to read more about how the model works, see here.
But saying the former vice president is the front-runner doesn’t really tell the whole story. He may be the most likely nominee, but he’s still a slight underdog relative to the field, with a 40 percent chance of winning a majority of pledged delegates7 by the time of the last scheduled Democratic contest — the Virgin Islands caucus on June 6. If one lowers the threshold to a plurality of delegates, rather than a majority, then Biden’s chances are almost 50-50, but not quite — he has a 45 percent chance of a delegate plurality, per our forecast.
I want to emphasize that there’s still a lot of room for another candidate to surge because nobody has voted yet, the primaries are a complex process, and frankly here at FiveThirtyEight, we’re a little self-conscious about how people interpret — or sometimes misinterpret — our probabilistic forecasts. The Democratic primary still features 14 candidates, and while most of them have little to no shot, there are still several fairly realistic possibilities:
So while Biden’s in a reasonably strong and perhaps even slightly underrated position, it’s slightly more likely than not that Biden won’t be the nominee. Sen. Bernie Sanders has the next-best shot, with a 22 percent chance at a majority, followed by Sen. Elizabeth Warren at 12 percent and former Mayor Pete Buttigieg at 10 percent. There’s also a 14 percent chance — about 1 in 7 — that no one will win a majority of pledged delegates by June 6, which could lead to a contested convention.
The model works by simulating the nomination race thousands of times, accounting for the bounces that candidates may receive by winning or losing states, along with other contingencies — such as candidates dropping out and polls moving in response to debates and news events. Like all of our models, it’s empirically driven, built using data from the 15 competitive nomination races since 1980.8
Since the primaries themselves are fairly complex process, the model is fairly complex also — which we mean as a warning as much as a brag. Models with more complexity are easier to screw up and can be more sensitive to initial assumptions — so we’d encourage you to read more about how our model works.
As an illustration of how one race can affect the following ones in our model, here are each of the leading candidates’ chances of winning a plurality or majority of delegates conditional on winning or losing Iowa:
|With an Iowa win||With an Iowa loss|
|Candidate||Majority Chance||Plurality Chance||Majority Chance||Plurality Chance|
Biden, for instance, would be a heavy favorite if he wins Iowa, with an 80 percent chance of a delegate majority and an 84 percent chance of a plurality. His majority chances would fall to 20 percent following an Iowa loss, however. Sanders would be a slight favorite to win a majority after an Iowa win, with a 61 percent chance, but his majority chances would fall to 8 percent with a loss there. Warren would also be a slight favorite to win a delegate majority after an Iowa win, but Buttigieg would not be (although his position would be substantially strengthened).
These scenarios account for Iowa wins of all shapes and sizes — big, emphatic wins and narrow, perhaps even disputed ones. With a landslide win in Iowa, Sanders might be a fairly heavy overall favorite for the nomination. If Iowa were a four-way pileup instead — with Sanders narrowly winning and Biden in a strong second place, for instance — Sanders’s projected bounce might not be enough to help him overtake Biden in national polls and the nomination could remain fairly open-ended.
Speaking of open-ended, the first three states all have highly uncertain outcomes. Biden is the nominal favorite to win Iowa, but has just a 33 percent chance of doing so.9 In New Hampshire, Sanders has a 31 percent chance and Biden is at 27 percent. And in Nevada, Biden has a 35 chance, with Sanders at 31 percent. Biden is a clearer front-runner in South Carolina — although even that lead might not be safe if he performed poorly in the first three states.
The model also plays out the rest of the primaries on Super Tuesday and beyond — although they’re subject to more uncertainty, both because they come later in the process and because they have less polling. In states with little or no polling, our model infers odds based on demographic and geographic factors — see the methodology primer for more.
For a flavor of how this works, here are the states and territories that the model thinks each of the four leading candidates is the most likely to win.
|Democrats Abroad||19||Democrats Abroad||16|
Biden’s strengths are concentrated in the South, among states with large numbers of black voters. Sanders and Warren are expected to perform well in New England and in western states such as Colorado and California, where the Democratic electorate tends to be pretty liberal. Buttigieg’s strongest states figure to be largely white states in the Midwest and otherwise in the northern part of the country.
We’ll have a lot more to say about the forecast in the weeks and months ahead. But let me conclude by briefly considering the forecast from each of the major candidates’ perspectives, tackling each one in 100 words or less.
Biden. The optimistic case for Biden is fairly simple. He’s ahead in national polls. He’s also ahead in our “fundamentals” calculation. (Although Biden hasn’t raised all that much money, he has by far the most endorsements.) His strength among black voters will help him in the South, where none of the other candidates look particularly strong. So a win in Iowa would put Biden in a commanding position. And a loss there could be more survivable than it would be for another candidate. Still, Iowa is more likely to hurt him than help him, according to our model.
Sanders. Sanders’s early-state polling is fairly robust. He probably wouldn’t have any problem parlaying an Iowa win into a sequel in New Hampshire, and our model likes his position reasonably well in Nevada also. California is another potential strength for Sanders on Super Tuesday, as a source of both delegates and momentum. All that said, perhaps the biggest question about Sanders — namely, how would the establishment and voters react if he appeared to be on the verge of winning the nomination — remains unanswered, and it’s not necessarily something our model can answer by itself.
Warren. The conventional wisdom about Sanders is fairly bullish, while being fairly bearish on Warren. But it’s worth keeping in mind that there are only a few points separating them in the polls, nationally and in the early states. They’re an important few points — in part because they coincide with the 15 percent threshold that Democratic rules require candidates clear to win delegates. That’s part of why our model gives Sanders roughly double Warren’s chances of securing a delegate majority. But even a small-ish burst of momentum for Warren could restore her to a highly competitive position.
Buttigieg. Buttigieg can win Iowa — but he also runs the risk of stalling out afterward. The problem isn’t in New Hampshire, where his position is nearly as strong. But Buttigieg is weak among nonwhite voters, especially black voters, which makes Nevada and South Carolina uphill battles for him. With that said, Buttigieg is the sort of candidate who the model figures could get a relatively large bounce from wins in Iowa and New Hampshire. In general, the lower a candidate’s standing in national polls, the bigger the bounce they get from early-state success.
What about … Klobuchar? Sen. Amy Klobuchar has picked up a percentage point or two in the polls since the December debate. But if that’s all she gets, it’s probably a case of too little, too late. Her position is not hopeless — the model does have her as the fifth most likely winner. But the model simply thinks it will take a lot to leapfrog four other candidates. With that said, there’s been little polling recently, and a single strong poll in Iowa could change the equation for Klobuchar.
What about … Bloomberg? If you’re a Michael Bloomberg optimist, you could point toward the 14 percent chance that no candidate wins a delegate majority as a bullish sign. The former New York mayor’s plan clearly involves hoping for a murky outcome in the early states and playing the long game. But there are many, many questions here. The first four states probably will produce a clear front-runner or two, and even if they don’t, it’s not clear why Bloomberg would emerge as the alternative. Still, his unconventional strategy is difficult to model.
What about … Steyer? Billionaire Tom Steyer has risen in recent polls of Nevada and South Carolina after a monthslong advertising barrage there. It’s not quite clear what that gets him, though. On the one hand, his position will be weaker in those states by the time they get around to voting if he hasn’t also performed well in Iowa and New Hampshire. On the other hand, he hasn’t invested in Super Tuesday states (as Bloomberg has) to follow up on any potential success in Nevada and South Carolina. He’s worth watching, but the model doesn’t see a clear path for him.
Enjoy the weekend — and the CNN/Selzer/Des Moines Register poll that is scheduled to come out on Friday night — and we’ll be back at you with more updates soon.