Who could replace Biden as Democratic nominee?

BBC:

Democratic lawmakers are calling on President Joe Biden to end his re-election campaign after his botched debate against Republican challenger Donald Trump.

On Wednesday Peter Welch of Vermont became the first Democratic senator to call for the president to end his campaign.

Hollywood actor George Clooney, a major party donor, joined the chorus.

A series of opinion polls since the debate suggest Trump may be edging ahead in key states.

President Biden has continued to insist he’s staying in the race. But recent events have raised questions about how he could be replaced – and who would replace him.