A nonprofit funding a ballot measure campaign to establish nonpartisan elections is denouncing allegations that the group ran afoul of state campaign finance law.

Amendment V opponents say outside groups TakeItBack.Org, of Sioux Falls, and New York-based Open Primaries violated state law by contributing money to supporters that was collected for the purpose of influencing the ballot question.

Amendment opponent Will Mortenson, chairman of No on V, says any illegal contributions should be returned.

Jeremy Gruber of Open Primaries called the allegations false, saying a fundraising tool under scrutiny solicited all donations directly to the Vote Yes on V campaign.

A TakeItBack.Org spokesman says the group believes it's complying with disclosure requirements, but is checking to make sure.

A Secretary of State's office spokesman didn't immediately return a request for comment.