Incumbent Democrat.
Zero chance Democrats win in 2028 if Biden wins re-election in 2024. And running against an incumbent Republican in 2028 probably wouldn't end well either.
Harris is presumably the incumbent Democrat in this scenario, and that means she won in 2024 so her vulnerabilities were probably greatly exaggerated.
A Republican primary following a term-limited Trump would look like a clown car. Everyone would be trying to replicate the magic that he had. Democrats would similarly be in a very obnoxious primary and would have a massive progressive/moderate schism after Biden loses to Trump. It would be pretty ugly.
Incumbent Democrat/Harris gives the Democrats the obvious incumbency advantage, plus I really don't think voters are going to produce THREE one-term presidents in a row unless she screws up royally.
Incumbents typically perform best, but Harris being the most likely incumbent Democrat to be nominated in 2028 weakens this assumption.
If Harris is the incumbent heading into the 2028 election, doesn't her victory in 2024 mean that she's probably not as weak a candidate as previously thought?