Three weeks after the political earthquake of Vice President Kamala Harris replacing President Joe Biden as the Democratic presidential nominee, the effect on Senate races is still somewhat murky.

We still have scant polling, with some campaigns waiting until Harris’s honeymoon period wears off or after she begins her tour with new vice presidential pick Gov. Tim Walz. But the fundamentals of the Senate map that persisted even through Biden’s lows remain intact: Endangered Senate Democratic incumbents are continuing to outperform the top of the ticket. And with Harris ushering in a wave of enthusiasm for their beleaguered base, the margin Democrats in red or swing states need to overperform by has now likely narrowed.

As we wrote in the immediate aftermath of Biden’s disastrous debate performance, there was not a mass freakout happening — yet — over how his backsliding numbers would affect Senate races. But the longer he refused to step aside and voters remained focused on his age and health, concerns began to mount. There were palpable worries among Democrats we talked to the week of

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