Biden 2020 / Trump 2024:
1. People who fell down one of the anti-vaxx, CRT, or anti-trans conspiracy rabbit holes since the election.
2. People who think that we haven't gotten any less divided since Biden took office, credit the pre-pandemic economy to Trump, and figure "If we're going to be divided anyway, might as well have a good economy."
Trump 2020 / Biden 2024:
1. Conservatives for whom January 6th was the red line.
2. Pro-choice people who thought Roe was settled law.
3. Some moderates who tend to favor incumbents.
#2, for both groups, are going to be the largest factor IMO.
Let me examine it.
Category 1: Probably people from Marin county or DC suburbs, so their vote is practically immaterial.
Category 2: Now that is the big one. Trump is though the most pro-choice republican nominee in a while and the economy is very good, that might complicate things.
Category 3: I'm not convinced that's not a myth. Trump, Bush Sr. and Carter didn't get any.