Kamala Harris’s Debate Bounce Is Fading

We’ve documented for years how polls tend to rise and fall — in what are often fairly predictable patterns — after events like debates and conventions. In general, what suddenly goes up in polls tends to gradually come back down after a matter of a few weeks. Conventions typically produce polling swings of 4 to 6 percentage points toward the party that just nominated its candidate, for instance — but the polls usually revert back to about where they were before after a few weeks.

We’ve also repeatedly seen this...