Convince Biden to drop out of the race about a week before the Democratic National Convention, citing health reasons, and name a millennial candidate who grew up on a farm with wind turbines and solar panels, before enlisting for 2+ terms, and moving to a middle-class area of a blue state after separating. Turn the convention into a media frenzy, energizing the Democratic base.
Undercuts Trump among rural Americans and veterans. Reverses all of Trump's old and senile attacks against Biden, as he suddenly becomes the geriatric candidate. Keeps all of Biden's supporters, while stepping away from the "genocide" criticism.
Basically, if Biden backs out a week before the convention and names someone in their 40's, they can run on a platform of "Ok, boomer" and reach 270.