text:  This is All Things Considered from NPR News. I'm Elsa Chang. In the aftermath of President Biden's disastrous debate performance last week, Democrats have both privately and publicly stated that he should step down from the ticket. The Biden campaign has been adamant that he will not drop out. But if he did, there is a long list of younger Democrats who may be considered as his replacement. NPR White House correspondent Deepa Shivaram has more.