Marriage equality gains across the country have created significant divisions within the Republican Party, with  right-wing activists threatening to leave the party and actively campaign against some lawmakers over their support for same-sex marriage.

This week, during an appearance on the conservative radio show Mission America, Phil Burress—an influential right-wing activist in Ohio—said that if more Republicans announce their support for marriage equality or offer anything less than steadfast opposition to same-sex marriage, he and other conservatives will leave the GOP.

“You can put a cross on the grave of the Republican Party if they ditch this issue, it would be the same thing with the life issue,” he said. “If they’re not going to stand for life and natural marriage, Huckabee was the first one that came out and said that he would not only leave the Republican Party but he’ll take everybody with him. The Republicans had better take this serious because this is a non-negotiable issue with us.”

This comes in the wake of the Republican Party’s support of two openly gay candidates for Congress that led to conservative activists saying they will make a “concerted effort” against Republican candidates they say threaten the party base.

Burress is a leader of Citizens for Community Values, the Ohio affiliate of the anti-gay Family Research Council and of Focus on the Family’s political arm, Citizenlink. When Ohio Sen. Rob Portman (R) expressed his support for marriage equality, Burress was part of a chorus of right-wing outrage that excoriated the senator and called for Portman to place his son in so-called conversion therapy.

Calls for conservatives to leave the GOP based on marriage equality stands in contrast to a growing number of young Republicans who hold more progressive views on marriage equality.

More than 60 percent of Republicans younger than 30 are in favor of same-sex marriage, according to a Pew study. Support for same-sex marriage has increased among all demographics, including among self-identified Republicans, conservatives, and every Christian denomination.

Burress, during his Mission America radio interview, predicted that Portman would lose his bid for reelection in 2016 because of his support for marriage equality. “I find this rather amusing, he stands no chance whatsoever. He’s seen his numbers, he knows what his numbers are and so do we. He is basically lost, he’s not even going to hold his own seat in ’16,” Burress said.

Portman was elected to the Senate in 2010 with nearly 57 percent of the vote. A February Quinnipiac University Poll found that 38 percent of Ohio residents approved of his job performance, while 32 percent disapproved.