N.H. Rev. Stat. Ann. § 666:5

The attorney general may appoint a person to act as challenger of voters at any polling place in the state at a state election. A statement signed by the attorney general appointing him shall be sufficient evidence of the authority of any such challenger. He shall be assigned by the moderator or other election officer presiding at the polling place to such position or positions within the polling place as will enable him to see and hear each voter as he offers to vote. Nothing herein contained shall deprive any other person of the right to challenge a voter as provided by law.