Trump claimed that "Voting machines were not touched" by Russians in the 2016 election. Tanden said that was a "lie." The media massively amplified claims of Russian election hacking that never panned out: https://www.nytimes.com/2017/09/01/us/politics/russia-electi.... They played fast-and-loose with terminology, saying that "Russia hacked the 2016 election" when they meant that Russia hacked and leaked DNC emails. (Part of the problem here is that the media has taken to regurgitating Democratic talking points. Saying "Russia hacked the 2016 election" is a clever way for an Democratic activist to describe what happened, but its misleading when that same "hacking" terminology is used by the media.)
Nalder said that, without impeachment, Trump would "rig" the 2020 election: https://www.bloomberg.com/news/articles/2019-12-08/nadler-sa...
And people believed them. Even as of 2018, 66% of Democrats believed that "Russia tampered with vote tallies in order to get Donald Trump elected President": https://today.yougov.com/topics/politics/articles-reports/20...