 As this all unfolds in real time, this historical moment, Democrats are making a calculation that, yes, there are real concerns about President Biden in some quarters. At the same time, they're alarmed about Trump. They see him as a threat to democracy. And they buy the argument from many Biden people that there is only one person who has ever beaten Trump. And he's running right now and should continue to be the nominee. CBS News election and campaign correspondent, chief correspondent Robert Costa.