NeilD & Stilly, you make a lot of good points.

The prospect of Trump being re-elected is dire. Personally, I think that Biden is your best chance of defeating him.

Unfortunately, even though I think Harris would make a great President, I also think that the probability of a lot of the white male voters and a significant chunk of white female voters would think twice about voting for a woman, especially as she is a woman "of colour". It was hard enough getting our first female Prime Minister in Australia, and then she was subjected to gender bias, even by other elected politicians. She achieved a lot, but could have had a more pleasant and more productive experience than she did.

Strategically, I think the best plan is to keep Biden as the candidate, hopefully he gets elected and then if his health or capability declines during the Presidential term he can step down and Harris will take up the role.