TIME MAG: More than 300 veteran Republican lawmakers, operatives and consultants have filed a friend of the court brief at the Supreme Court in support of same-sex marriage late Thursday.

The amicus brief organized by former Republican National Committee Chairman Ken Mehlman, was filed for the four same-sex marriage cases the Court will hear on April 28 that could legalize the unions nationwide. In 2013, Mehlman marshaled a similar effort for the case that overturned California’s Proposition 8, which had banned same-sex marriage in the state. Among the signatories are 23 current and former Republicans members of the House of Representatives and Senate and seven current and former Governors. Sens. Susan Collins and Mark Kirk have signed onto the brief, as has Massachusetts Gov. Charlie Baker and former Utah Gov. Jon Huntsman. Other notables include former New York City Mayor Rudy Giuliani, retired Gen. Stanley McChrystal and billionaire GOP mega-donor David Koch.

In an interview with TIME, Mehlman pointed to the growing national consensus and within the GOP on the issue. "There's been an increase since the last time in public support for marriage equality across all ideological, racial, and political groups," he said.

The brief makes a conservative case for the court to strike down same-sex marriage bans in Michigan, Ohio, Kentucky and Tennessee, arguing they are "inconsistent with amici's understanding of the properly limited role of government."