The party could hold an open audition for the nomination process. Candidates who raised their hands would hold two or three debates against one another. They could give speeches and hold rallies. And Democrats could vote in straw polls sponsored by donors in a combination of virtual locations and physical ones that reflected the demographic breadth of the Democratic Party — say, in Atlanta, Phoenix, Pittsburgh and one or two more rural locations. Voters would also express their opinions in regular opinion polls.

Delegates could take this information into account at the Democratic National Convention in Chicago and make a more informed decision. This plan would require Mr. Biden to declare his intention to exit the race sooner rather than later.

It’s not a great plan. But there is no great plan left. At this point, any Democrat would likely be an underdog to Mr. Trump. Not because Mr. Trump is popular, which he very much isn’t, but because it’s hard to imagine a replacement being fully prepared for the race.