True. But historically, you would expect to see higher levels of interest in the challenger party's primary if the incumbent were likely to lose. This is true even if the challenger party's nomination was already wrapped up. The reasoning is because the incumbent's party would be less enthusiastic.

Trump has overperformed throughout this primary season compared to previous incumbents.

Edit: besides, even if both nominations are done deals, Trump is at ~826K to Biden's ~640K. Bernie is taking ~160K and Tulsi ~30K which is hugely bad news for Biden this late in the cycle.

True. But historically, you would expect to see higher levels of interest in the challenger party's primary if the incumbent were likely to lose. This is true even if the challenger party's nomination was already wrapped up. The reasoning is because the incumbent's party would be less enthusiastic.

Trump has overperformed throughout this primary season compared to previous incumbents.