Biden ending his campaign is one thing; Biden *resigning* would mean:
a) endless GOP House "investigations" on Kamala Harris "covering up" Biden's mental state;
b) the GOP House and broken Senate both have to confirm the new VP, they won't, and GOP will blame Dems.
It's simply not a viable plan.
I think you basically have the same issues with Biden withdrawing; it practically invites the House GOP to ask how Biden can be fit for office, yet unable to campaign.
Also, the DC press won't care—they'll run endless "cover up" stories in either case.
That one at least has an easy answer: Biden is withdrawing from the campaign because he's fine now, but he's thinking about what he might be like four years from now. He's being a prudent steward, etc.
“I have the health & energy to be president. I have the health & energy to run for president. I have the health & energy to do both at once. What I don’t have is the health and energy to do both at once *while* working to stop a corrupt faction of the Supreme Court which has endorsed a coup”
Ok, but he'd better have a good and true reason for why this wasn't the case just 4 mos ago when he ran in primaries.
Otherwise: "We told you so! Dems knew it, and they've been lying to you the last 4 years. What else are they lying about?"
Yeah, this isn't hard. He did what he set out to do! He saved the country from Trump. He deeply wanted to do it again, but he knows it's better now to pass the torch to the VP so she can lead us into the future! Do it for Old Joe, and blah blah blah. It's an EASY sell!
This is the story that gets written if he makes the decision not to run a year ago, not now, after he’s been pushed out by his party after bombing a debate. What gets written now are endless insider “how did we get here?” pieces.
Those voters don't know about any of this yet, lol! They'd still be surprised to hear Biden's in any trouble. (Doesn't mean he might not be fucked. Elite circle jerks are a hell of a drug.)
And I think this is basically true, that he's functioning well as president but doesn't have another 4 years in him! I mean, I'm confident that his administration will also do fine if he can't do the job, but that's not a good position to run on.
But what do we care whether the GOP says Biden is unfit if he's not running for reelection? I don't think this would happen. Once he became a lame duck he would get an immediate halo like Obama in 2016.