N.H. Rev. Stat. Ann. § 669:48

No person shall vote in any caucus unless his name is on the checklist used by said caucus except as provided in RSA 669:46. No person shall vote using the name of any other person; and no person shall vote in the caucus of more than one political party, or, having voted in the caucus of a political party, sign the nomination papers of any other political party for that election. No person shall vote in any caucus unless he intends to support the ticket of the party holding the caucus at the next election.