They call those "poll watchers" in Minnesota. And yes, every party is allowed to place poll watchers at any/all precincts. Poll watchers are also allowed to cha

They call those "poll watchers" in Minnesota. And yes, every party is allowed to place poll watchers at any/all precincts. Poll watchers are also allowed to challenge the registrations of any individuals coming to vote. I don't remember the exact details around it, but they aren't powerless. I remember one election in particular where I was working a mixed-race, poor neighborhood precinct in Minneapolis. The Democratic poll-watcher was convinced the Republican one was going to challenge every single voter and paralyze the precinct, preventing hundreds from voting. The Republican poll watcher was convinced that Democrats were going to bus in thousands of paid illegal black voters from Wisconsin. Of course, neither of these things happened.