 There's a lot of time left before November's election. Trump's popularity has soared. And any Democrat candidate will have a tough time winning against the momentum behind him. Democrats aren't likely willing to sacrifice one of their up-and-coming party darlings, like California Governor Gavin Newsom or Michigan Governor Gretchen Whitmer, on a long-shot chance in the White House. This leaves Biden as the only one capable of taking the hit Democrats face.