The line between the primary and the general has gotten too blurry
The 2024 primary season has been weirder than I think anyone expected. The two parties feel like they have a lot of internal tension, but with a current and a former president seeking their parties' respective nominations, it hasn't been very competitive. One result of this has been that we've been looking for clues to the general — the Trump-Biden rematch — in the primary results. In turn, this has meant some overinterpretation of primary results — it's not a given that people who cast a vote for another candidate won't come home in the general.
It's also hard to compare the internal dynamics of the two parties and apply those to predictions for the general. Dean Phillips' candidacy, for example, has presented himself as a moderate, pragmatic alternative to Biden — but he's mostly emphasized the age difference. Some Democrats have been unhappy with the policies of the administration, especially on the Israel issue, but there hasn't been a progressive candidate to challenge him. Trump, on the other hand, has faced — and beaten — experienced opponents with more substantive disagreements. This makes it harder to use the primary as a direct roadmap to what the candidates' liabilities might be in the fall.
—Julia Azari, 538 contributor