DENVER –  A gay couple from New Jersey suing a group that used their engagement photo says they cringe when they see the image after it was used in an attack mailer against a Colorado Republican in a legislative primary.

The Southern Poverty Law Center filed a federal lawsuit Wednesday in Denver on behalf of Brian Edwards and Tom Privitere against Virginia-based Public Advocate of the United States. The group has commented on the lawsuit through email requests.

The photo shows the couple holding hands and kissing with a New York City skyline as a backdrop.

The photo was used in mailers in a June primary election against Sen. Jean White, who supported a civil union bill that was blocked in the state House. White lost the primary.