text:  The president's goal here is to hold Donald Trump accountable, to remind voters of the chaos of the Trump presidency, and he will argue that he is a threat to democracy. The president, I'm told, is also preparing to walk a fine line here. He knows that Trump is going to try and go after him. He has to show he's a steady leader and not get rattled. The muted mics may help with that. But perhaps what most people are going to be watching most closely, Joe Biden has to bring it. He has to show voters concerned about his age that he is up for this, and he has to convince those panicky Democrats that he can win.