A Trump supporter with the Twitter username @queeneliza0907 was present for the candidate’s Waukesha visit and tweeted the video linked to in the above tweet that showed Trump mingling with other supporters outside the polling place. Sources say Trump actually entered the polling place. One video shows him clearly within 20 ft. of the door.
He is allowed to go inside as long as hes not campaigning. Candidates are not banned from polling places only campaigning within 100 feet of a polling place.