I would bet the head of our Texas Rangers has met with Gov. Perry and they have their marching orders from Perry. The Rangers have a reputation for not putting up with crap. There is a saying for the Rangers - one riot, one Ranger.
There is a constable for every precinct and a call from an election judge that someone is not staying behind the distance marker, will get the constable there to remove them. Any resistance will get them put in the county jail, no matter what country they come from, UN or not.