First, one thing I haven’t emphasized enough is Harris’s inferior position relative to where fellow Democrats [Hillary Clinton and Joe Biden] were polling at this point in time the last two elections. Andrew Sullivan summarized it this way:
At this point in 2020, Joe Biden, with far fewer resources than Harris, was 10 points ahead of Trump, and finished around 8.4 points ahead in the polling. Biden won the actual election by 4.5 percent, almost half the margin the polls predicted. At this point in 2016, Hillary Clinton was 6 points ahead, finished 3.6 points ahead in the polls, and ended up 2.1 percent ahead in the popular vote. ….
