538 Election Update: Biden Surges In South Carolina

After former Vice President Joe Biden finished second in the Nevada caucuses, someone at his post-election speech shouted out, “Comeback kid!” It seemed like an odd claim at the time — Biden finished more than 26 percentage points behind Sen. Bernie Sanders (going by county delegates). But based on the latest polls, Biden may indeed be experiencing a comeback in South Carolina, which votes on Saturday.

As Nevada went to the polls last Saturday, the FiveThirtyEight forecast considered Sanders the slight front-runner in South Carolina, with a 1 in 2 (46 percent) chance of winning it. It gave Biden a 2 in 5 (40 percent) chance. Since then, in a reminder of how fluid primaries can be, Biden’s chances have skyrocketed. As of Thursday at 5:38 p.m. Eastern (😉 , Biden has a 14 in 15 (94 percent) chance of winning the Palmetto State, while Sanders’s odds are down to 1 in 20 (5 percent).tps://fivethirtyeight.com/features/election-update-biden-surges-in-south-carolina

The first hint of Biden’s comeback came two days ago: Biden had only a small lead on Sanders in our South Carolina forecast at the time, but the first survey conducted entirely after Nevada, from Public Policy Polling, showed Biden up 15 points. At that point, the poll was an outlier. Well, not anymore. Since Wednesday, we’ve gotten six new polls of South Carolina, most of which have given Biden commanding leads.

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It’s tempting to chalk up Biden’s comeback to his performance in Tuesday’s debate or his Wednesday endorsement by Rep. Jim Clyburn, who carries a lot of weight in South Carolina Democratic politics. But in reality, the polls above were mostly conducted before either of those two events. Instead, the dividing line seems to be the Nevada caucuses. In six South Carolina polls conducted between New Hampshire1 and Nevada, Biden averaged 26 percent and Sanders averaged 22 percent. In the six polls conducted entirely since Nevada,2 Biden has averaged 35 percent and Sanders has averaged 20 percent.

It’s certainly odd that Biden, and not Sanders, would have gotten a bump out of a state where Sanders won nearly twice as many raw votes, but that’s what it looks like. Perhaps it is the manifestation of establishment backlash against the suddenly-real prospect of Sanders becoming the nominee.

And accordingly, that prospect is now getting less likely again. As FiveThirtyEight editor-in-chief Nate Silver wrote earlier today, Biden winning South Carolina — especially by a big margin — would put him in good position to win, or at least net many delegates from, the many Southern states that vote just three days later, on Super Tuesday. That could set the table for a drawn-out nomination fight between Sanders and Biden — one that could even lead to a contested convention.