DENVER (AP) — A gay couple from New Jersey is suing a group that used their engagement photo in an attack mailer against a Republican Colorado state lawmaker who supported civil unions this year.

The couple and their attorneys plan to talk about the lawsuit Wednesday morning outside federal court in Denver.

The Southern Poverty Law Center is filing the lawsuit on behalf of the couple against the Virginia-based Public Advocate of the United States. 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 involving Sen. Jean White, one of a handful of Republicans who supported a civil union bill that was blocked in the state House. White lost the primary.

(© Copyright 2012 The Associated Press. All Rights Reserved. This material may not be published, broadcast, rewritten or redistributed.)