A Republican group that supports GOP candidates who back marriage equality is campaigning for a change to the party's national platform on the issue.

According to POLITICO, the American Unity Fund is reaching out to a number of Republican National Committee (RNC) members on the issue.

“We are working to ensure that each and every delegate is empowered to vote their conscience and truly craft an inclusive Republican Party platform,” Jerri Ann Henry, who heads the group's convention campaign, told the outlet. “We need to be inclusive.”

In 2012, Republicans meeting in Tampa ratified a platform which supported a federal constitutional amendment defining marriage as a heterosexual union and chided judges who struck down state marriage bans that excluded gay couples, calling the rulings “an assault on the foundations of our society.”

The American Unity Fund has the backing of billionaire investors Paul Singer, Dan Loeb, Seth Klarman and Cliff Asness.

Singer, who is straight but has a gay son who married his husband in Massachusetts, the first state to legalize such unions, is considered among the most important Republican donors nationwide. In 2012, The New York Times reported that he had given nearly $10 million of his own money toward efforts to legalize marriage equality in several states.

“Atmospherically and tonally, it's part of the landscape of so-called harshness,” he told the Times in 2012 about the effort to move the party on the issue.

Ed Martin, president of the social conservative Eagle Forum, told POLITICO that evangelicals opposed to marriage equality are “prepared for the fight. It's hand-to-hand combat.”

He added that the fight might be difficult, because “the Paul Singers of the world are spending millions.”