If Biden is to step down, I doubt he’ll do it before the Republican Convention, and he might leave the question float in the air.
After all, Trump is going to have to choose VP not knowing if he’s running against Biden or Harris, or even someone else. That can only make his choice more complicated. Further, the Republicans will have to be somewhat careful in their attacks on Biden, since if he is cognitively impaired, they don’t want to push him out of the race. They would rather push him out of the September debate or hope to embarrass him again. Lastly, the Republican strategists, well versed in attacking and spreading lies, will have a hard time doing that if they don’t know exactly who the enemy is.
But, wait there’s more!
If Biden decides not to run right after the Republican Convention or, better yet, an hour before Trump gives his acceptance speech, the Democrats will steal the news cycle. They will garner all the press, as that history-making event unfolds. And when that event unfolds, if Biden has decided to actually step down, the United States will have its first female President. The Republicans will be all but invisible in that news cycle, giving the Democrats a chance to build momentum.
Of course there are risks for the Democrats (such as an impaired Biden refusing to step down or a very divided Democratic Convention) , too, but my feeling is that if Biden chooses to step down, he will have all the ducks lined up and the Democrats will operate in a united fashion, despite the big egos involved.