John Eastman, chairman of the National Organization for Marriage (NOM), on Monday said that marriage equality supporters are being “overly optimistic” as the issue heads back to the Supreme Court.

In an NPR story about 2014 being a banner year for supporters – the number of states allowing gay couples to marry increased from 18 to 35, plus the District of Columbia, in the previous 12 months – Eastman, a law professor at Chapman University, said that the Sixth Circuit's ruling upholding bans in Ohio, Michigan, Kentucky and Tennessee was a game-changer.

The ruling created a split between appellate courts, all others having sided with plaintiffs, increasing the likelihood that the high court would consider one or several of the cases in the new year.

“I think the proponents of redefining marriage are overly optimistic in their anticipation of an ultimate ruling in their favor,” Eastman said.

“As long as there's a fight to redefine the institution of marriage that runs contrary to your human nature, human nature's going to have a way of fighting back,” Eastman said of emerging strategies aimed at undermining the rulings, such as a proposal in South Carolina that would allow public officials to refuse to issue a marriage license based on their religious convictions.

Eastman was unsuccessful in legal attempts to block rulings in North Carolina and Oregon axing state bans from taking effect.