Nate Silver and the NYT editorial board have both called for Biden to step down.
By every metric Biden is performing significantly-worse compared to his 2020 run against Trump. Biden needs to step down now while we have time.
This gives a huge opportunity for Democrats to take back the narrative and inject some excitement into nominating a fresh, younger, face. Free viral media attention would go on every day until the election and Democrats can turn around and say, "we listened to the electorate's concerns on age, are responding." Meanwhile the Republican propaganda machine wouldn't have prepared talking-points lined up.
Finally, look, I voted for Biden and I'd vote for a corpse if it came down to it, but it's not me you have to convince. We elected Biden because he said he'd take the fight to the bully. He's not the Teddy Roosevelt fighter we need to push a bully back. He's not convincing ANY battleground state swing-voters with a performance like that which will resonate over any subsequent teleprompter speeches he may give thereafter.
Edit: Hey folks, if you have the energy to down-vote, would you mind mustering a bit more to actually put your convictions to the test and discuss with me? I can otherwise only conclude you've got no substantive rebuttal and this is denial acting out. I'd appreciate it. Thank you.