Actually, your second link doesn't say what you think it says. It says that people believe that Democrats believe that, not that Democrats believe that. Yes, it seems a weird thing to poll about.

Your fourth link is misleading. You've picked a link from a moment in time when Barr had released his summary of the Meuller report but Meuller's criticism of Barr's summary as being inaccurate had not been released.

The second link's poll includes a breakout of Democrats' beliefs in what Democrats believe, in addition to the overall figures. So 65% of Democrats agreed at the time that Democrats don't accept Trump as the legitimate president. I realize it's not the same exact question, but it is similar. There are also other polls that I didn't include that you can find with similar results.

As for the fourth link - I am not sure of the timing of that particular poll (I just pulled that from a search earlier), so I'll have to take your word on that. Thanks for pointing it out.

The "whataboutism" argument doesn't refute the initial claim. It's simply changing the subject and is effectively surrendering the point.

It doesn't refute it but sums up well the American political culture.

I'm not refuting it. I am pointing out that this is a pattern with much precedent, and is not restricted to Republicans or conservatives. A number of comments in this discussion seem to be ascribing belief in improbable scenarios to one political side. If anything, I would say that election denialism is a tit-for-tat game that is now reflecting back the same disbelief that was shown in prior elections. Furthermore, the GP comment suggested that half of the population holding a "crank denialism" is something new. My evidence shows it is clearly not something new.