Biden's unpopularity was mostly around him being old as he'll and as a result of being old he wasn't able to be out there selling the American people on his achievements and he didn't look like he had 4 more years in him.I've never liked Kamala, but I think it's unfair to blame it on her.
Running the VP of an unpopular President is generally not a good idea. You can double that effect when there is high inflation, inflation is just an incumbent killer (ask Jimmy Carter).
Kamala harris was unpopular before. In fsct she was so unpopular she was outperformed by basically everyone when she ran for president in 2020z.
I said it back when it happened that pyzhinh gerout there and giving her the nomination was going to be bad.
One because she was so disliked that people weren't even telling Joe to step aside so she'd be president and the defacti nominee with experience.
Two, because it opens up the same complaints of folks feeling like voting doesn't matter and candidates are appointed thus depressing turnout.
Kamala has no natural base...

