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Trump shocked the world four years ago in Wisconsin—and he has the same odds to do it again in Pennsylvania

November 3, 2020, 3:52 PM UTC

All eyes are on the Keystone State. If Democratic nominee Joe Biden wins Pennsylvania, he removes President Donald Trump’s most feasible path to a second term—and would force Trump to win a Midwestern state like Michigan or Wisconsin where the President is faring much worse.

FiveThirtyEight editor-in-chief Nate Silver gives Biden an 84% chance of winning Pennsylvania in his final 2020 forecast. But that is hardly bulletproof: Just ask Hillary Clinton whom FiveThirtyEight gave a 77% chance to win Pennsylvania, 78.9% chance to win Michigan, and 83.5% chance to win Wisconsin four years ago. Trump would go on to win all three, along with upsets in Florida and North Carolina.

In all, Biden is FiveThirtyEight’s favorite in seven states Trump won four years ago. That includes Arizona, Georgia, Florida, Michigan, North Carolina, Pennsylvania, and Wisconsin. If Biden can hold on to every state FiveThirtyEight projects he’ll win, he’d beat Trump in a 351 to 187 electoral vote landslide. FiveThirtyEight gives Biden an 89% chance of winning, up from the 71.4% it gave Clinton.

But what’s the result if the polling error in 2020 is identical to that in 2016? To find out, Fortune used FiveThirtyEight’s 2016 forecast vote share to calculate polling errors in 14 battleground states. Then we applied those 2016 state polling errors to states’ 2020 FiveThirtyEight forecast vote.

The result? Biden would still win, bringing in 320 electoral votes. In that scenario, he’d pull out narrow victories in five states Trump won four years ago, including Arizona, Florida, Michigan, Pennsylvania, and Wisconsin. While Trump would take Iowa, Georgia, North Carolina, Ohio, and Texas. (We recently tried this same experiment on RealClearPolitics poll averages and found a similar result).

But this scenario—despite the massive electoral vote tally—wouldn’t be the Biden runaway it appears. Applying a 2016 polling average, Biden would narrowly win Arizona (1.3 points), Florida (0.7 points), and Pennsylvania (0.3 points). The 60 electoral votes in those three states are what—in this scenario—would stand between Trump and reelection.

Simply put: Trump can win, but he’ll need to pull off an even bigger upset this time.

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