well, certainly there are people on both sides that have openly said, the only way my guy loses is if the other side cheats. I really hope it's not close. Unless one side blows the other out, this division will only get even more intense (hard as it is to believe). There are some, even in the face of a blowout loss, that will deny the legitimacy of the other side. But not that many, relatively.
I said this once before - I trace the hyper political division in this country to an event much earlier than most. It was before Trump, before Obama. November 2, 2000 - a mere 5 days before the Bush/Gore election - it was leaked that Bush had a DUI arrest some 25 years earlier. As many as 4 million evangelical voters stayed home on election day. Without that, Bush wins relatively easy, there is no Florida chad mess, no Supreme Court case, no absolute certainty on the left that the election was stolen. That's when all this hostility began. Which leads us to where we are now - with both me and you and many others agreeing that the losing side will regard the winner as illegit.