The historical pattern is clear, and ominous for Joe Biden and Democrats this year: The president’s party usually does poorly in midterm elections.
“It’s not quite a law of physics, but it’s probably as close as you’re going to get in the social sciences,” says Carlos Algara, a professor of political science at Claremont Graduate University.
Despite the persistence of this pattern, we know surprisingly little about why it happens — and why, every so often, it’s somehow averted….
