Here is the problem. They could wait another month and then heave Potato with the 25th. Harris would be President for a few months because that is the job. However, she would not win an election.
No one likes her. She could not win her own primary in her own state. The only reason she is there because she was liason with China, along with Joe when she was still a Senator.
So, really, the dems may not be as smart as they wish they were.
Also, too many people know about the ballot stuffing. They burned out that tactic by going overboard with it.
As someone else had noted, they already had enough ballots to elect HRC but the voter turnout suprised them. So, they countered that in 2020 with midnight dumps of 100,000s of ballots all single person, Biden.