The share of Republicans and Republican-leaning independents who believe that President Joe Biden’s 2020 election win was not legitimate has ticked back up, according to a new CNN poll fielded throughout July. All told, 69% of Republicans and Republican-leaners say Biden’s win was not legitimate, up from 63% earlier this year and through last fall, even as there is no evidence of election fraud that would have altered the outcome of the contest.
What was Robert mueller investigating?
Election interference, collusion with Russia and subsequent obstruction of justice.
You can believe trump should have been impeached for those crimes but again, that’s very different from saying the election itself was illegitimate. At no point in that investigation did Mueller (or, as far as I know any Democrat) argue that the votes were manipulated or altered once cast.
When Nixon was basically impeached (he resigned before that could happen as back then Republicans had integrity and would put party over country) it did not mean that the election itself was illegitimate.
https://www.washingtonpost.com/politics/hillary-clinton-trump-is-an-illegitimate-president/2019/09/26/29195d5a-e099-11e9-b199-f638bf2c340f_story.html
https://nypost.com/2022/01/10/harris-comms-chief-called-bush-43-illegitimate-president/amp/
You’ll note that neither of those articles has anyone saying the election was illegitimate.
In fact, the second one goes out of the way to say thay despite her disagreement with the call (Supreme court halting recounts strictly along party lines) the comms chief still respected the outcome, which is precisely the opposite of what trump did.