former Attorney General Eric Holder stated that we should “be concerned” about President Trump using paramilitary forces to suppress the vote
Though to be fair he was asked that direct question and basically said you can't trust Trump.
It is looking like the only way for Trump to win is limiting voting. So maybe mucking with the postal system, pretending there is a vote fraud emergency and calling on armed right wing militia to show up and intimidate, maybe get the grab-bag armed Feds out in force too. Who knows, but things could get awful funny on election day.