It’s allowed but the convention delegates choose the nominee. So, it’d probably have to be agreed ahead of time who the nominee would be and that the other contenders (and donors) would fall in line. Maybe if it’s Whitmer, they promise Harris and Newsome a cabinet secretary position. I’m not sure anyone has that sort of support, though. VP Harris would be the logical option for that sort of transition but she’s not popular and Trump is already making ads saying a vote for Biden means Kamala Harris will be president before the term is over.
I mean, anything is possible. We’re in uncharted waters. But to me, that’s also the problem. And we don’t know for sure why Biden was off in the debate. Maybe he had a cold. Maybe he’s so old, his childhood memories are in black and white. Maybe a month from now, there will have been a whole new news cycle and the debate will be forgotten.