Many voters may not be aware of the behind-the-scenes work that opposition research staff are doing this election cycle to raise concerns about both Republican and Democratic candidates who are in competitive races on the Nov. 6 ballot.

But Minnesota is one of only four states that America Rising PAC, a Republican opposition research outfit based in Virginia, is piloting with a targeted campaign that researches Democratic challengers and digs up property records, divorce records, Twitter posts, financial investments, old news articles and anything else they could potentially use against them.

America Rising started after the 2014 election as a Republican counterpart to American Bridge 21st Century, a liberal PAC that vows to hold Republicans accountable, according to a 2014 Washington Post article.

While opposition research has been around for years, these new efforts move the research done within campaigns and political parties to outside groups that can put undisclosed amounts of money and resources behind the mudslinging. Trackers follow candidates to parades and other events, hoping to catch opponents on camera saying something inflammatory. And a candidate's past controversial comments can be dug up, spread online or to reporters — with the hope it will help sway the race.