An interesting analysis by Simon Bazelon:
Between those two factors, it’s reasonable to assume that Democrats are looking at a vote share between 47% and 48.5% this cycle. This means Republicans will probably win the generic ballot by between three and six percent, and the median scenario is probably Republicans winning by around 4.5%. Since Joe Biden won by 4.5% in 2020, this would mean that the national environment has shifted 9 percentage points to the right.
Assume, for a moment, that there is zero ticket-splitting, and this swing is uniform across all elections. This would mean any Democrat in a state that Biden won by less than 9% will probably lose. That includes:
- Mark Kelly in Arizona (Biden +0.3)
- Raphael Warnock in Georgia (Biden +0.2)
- Catherine Cortez-Masto in Nevada (Biden +2.4)
- Maggie Hassan in New Hampshire (Biden +7.4)
So this would reduce Democrats to 46 or 47 seats. But the real nightmare is 2024.
Since the Reagan Era, Democrats have averaged roughly 51% of the two-party vote in Presidential elections. If Biden gets this percentage of the vote, and the correlation between the Senate and presidential vote stays at close to .95 (as it was in 2020), then basically every Democratic senator in a state Biden won by less than 2% who is up in 2024 is likely to lose.
- Jon Tester in Montana (Biden -16.3)
- Joe Manchin in West Virginia (Biden -29.9)
- Sherrod Brown in Ohio (Biden -8)
- Bob Casey in Pennsylvania (Biden +1.2)
- Tammy Baldwin in Wisconsin (Biden +0.7)
- Kyrsten Sinema in Arizona (Biden +0.3)
In addition, Debbie Stabenow in Michigan (Biden +2.8) and Jackie Rosen in Nevada (Biden +2.4) would likely be in toss-up races.
So what this says is that even if Biden wins 51% of the vote in 2024, the Democrats are likely to only hold 41 seats, maybe as few as 38.