You meant the "Democrat" party, though. Ironically, it is funny considering how anti-democratic the Republican party seems to have gotten in these lastest four years, after Trump got kicked out the office, anyways.
The democrat party is very unlikely to change Biden as their candidate for the presidency, to be honest. As a sample of it, Obama himself has already stepped up and said he completely backs his former boss (Joe Biden) and points out everyone has a bad day and only because Biden did not perform well, does not mean he won't be an able president.

Also, I have seen already some conspiracy theorist to suggest all this is according to plan in order for the party to switch Biden for Michelle Obama, which it would be a even worse pick than Biden. The country is simply not ready to have black woman as president, they were not to have a woman (Hillary), then are ever further from accepting Michelle.