Nick Kramer and Jason Cadek stand with their daughter Alice, 3, during a news conference Monday in Omaha. Cadek and Kramer are one of seven same-sex couples who filed a federal lawsuit on Monday asking the state of Nebraska to recognize their marriages and challenging the constitutionality of the state’s ban. (Nati Harnik/AP)

With marriage for same-sex couples now legal for more than half the U.S. population, advocates for other progressive issues are taking the lessons learned by marriage proponents and hoping to apply them to their causes.

“So many other movements are coming to talk to us,” Marc Solomon, the national campaign director for Freedom to Marry, said at a Tuesday event attended by The Washington Post. “I think we learned some things we can share with others.”

Solomon said he’s spoken with advocacy groups that work on environmental issues, sentencing reform, and education reform. On Tuesday, he published an article on The Hill with Dan Gross, president of the Brady Campaign to Prevent Gun Violence, about what gun control advocates have learned from the marriage movement.

“It’s not like we’re going to take the marriage playbook and apply it to guns,” Solomon said. “It doesn’t work like that.” But the same approach, with a “national campaign with a strong national narrative” and state-level work, could translate well to other issues.

“You had to get a critical mass of states and a critical mass of popular support,” he said. “We had to get the point on the board.”

Massachusetts became the first state to legalize same-sex marriage in 2004, and Solomon and Gross compared that to gun control and Washington state, where a ballot measure requiring background checks for all gun sales was passed by voters earlier this month.

“It was so much about momentum,” Solomon said about marriage for same-sex couples. “You get the first state then you hold the first state. Then we lost the second state, California.”

He said today, opposition to marriage for same-sex couples at the state level is muted, and pointed to Republican gubernatorial candidates in New Mexico, Michigan, Pennsylvania and Wisconsin who didn’t bring the topic up during the campaign.

“They wanted to stay away from the issue,” he said. “Believe me, eight years ago, that would have been a big thing.”