Still, Biden would be slightly favored to eke out a win in this scenario by winning one more more of those Sunbelt states. The most likely would be Arizona, which has less in common with Pennsylvania than the others.

Biden’s work wouldn’t quite be done if he won Arizona, though. Rather, his chances would be 85 percent, with a 5 percent chance of a 269-269 tie. But he’d be in pretty good shape. He could hold the other states Clinton won in 2016 and then flip either Iowa or a congressional district in either Maine or Nebraska, which award one electoral vote each. Alternatively, he could even lose another state Clinton won, like Maine or New Hampshire, if he carried a second Sunbelt state such as Georgia.

We’re getting into the weeds. But here’s the thing: Yes, Biden and Democrats should be nervous that he has only about a 5-point lead in Pennsylvania, the most likely tipping point state. Five points is more than a normal-sized polling error, but not that much more. And Biden does have some backup plans. A regional polling error in the Midwest or the Northeast wouldn’t necessarily doom his chances in states like Arizona, for instance. It wouldn’t be the blowout that Democrats hope for, but Biden would still retain an edge in the Electoral College even without winning his birth state.