Ahead of a potentially historic Supreme Court ruling, leading Republicans are vowing to defy any decision that sanctions same-sex marriage and are challenging the very legitimacy of the high court.

With a decision in Obergefell v. Hodges expected before the end of June, conservatives are confronted with what was only a few years ago a nearly unthinkable possibility: a Supreme Court decision that decisively makes same-sex marriage a constitutional right.

Fearing a huge setback to their cause, opponents of same-sex marriage, including some of the major contenders for the 2016 GOP presidential nomination, are darkly warning that they will not “honor” an adverse Supreme Court decision. Some are calling for civil disobedience. Others are moving to strip the Supreme Court of its authority to decide whether gay couples should be allowed to marry, while others have questioned whether the court has that jurisdiction in the first place. Sen. Ted Cruz (R-TX) has said that such a decision would be “fundamentally illegitimate.”

Those who are merely calling for a new constitutional amendment to enshrine marriage as between one man and one woman now seem almost quaint in their desire to use the ordinary constitutional process to counter the Supreme Court.

Here are some of the leading proponents of the new nullification:

Rick Santorum



Former Sen. Rick Santorum, on NBC’s Meet the Press last month, vowed to fight a Supreme Court decision in favor of same-sex marriage: “We’re not bound by what nine people say in perpetuity.”

“I think it’s important to understand that the Supreme Court doesn’t have the final word,” Santorum told viewers. “It has its word. Its word has validity. But it’s important for Congress and the president, frankly, to push back when the Supreme Court gets it wrong.”

Santorum is among the signers of the anti-gay marriage pledge being circulated by a group associated with the website DefendMarriage.Org. The group recently placed a full-page ad in The Washington Post with an open letter to the Supreme Court promising civil disobedience if the court struck down bans on gay marriage.

“We will not honor any decision by the Supreme Court which will force us to violate a clear biblical understanding of marriage as solely the union of one man and one woman,” the letter said. Its originator, Baptist pastor Rick Scarborough, has promised his fellow signers — some 50,000 people by the website’s count — will “resist all government efforts to require them to accept gay marriage, and they will accept any fine and jail time to protect their religious freedom and the freedom of others.”

Mike Huckabee



The former Arkansas governor also signed the DefendMarriage.Org civil disobedience pledge, and suggested that if elected president, he would ignore a Supreme Court ruling in favor of same-sex marriage.

“Presidents have understood that the Supreme Court cannot make a law, they cannot make it, the legislature has to make it, the executive branch has to sign it and enforce it,” Huckabee told Fox News’ Chris Wallace. “And the notion that the Supreme Court comes up with the ruling and that automatically subjects the two other branches to following it defies everything there is about the three equal branches of government.”

Ted Cruz



In addition to proposing the more temperate course of a new constitutional amendment to limit marriage to straight couples, Cruz introduced a bill in the Senate that would bar federal courts from weighing in on marriage until that amendment was passed, Bloomberg reported in April.

“If the court tries to do this it will be rampant judicial activism. It will be lawlessness, it will be fundamentally illegitimate,” he said during an Iowa campaign stop earlier this spring.

Ben Carson



Ben Carson has expressed doubt that a Supreme Court decision favoring same-sex marriage would need to be enforced.

“First of all, we have to understand how the Constitution works. The president is required to carry out the laws of the land, the laws of the land come from the legislative branch,” Carson said in May. “So if the legislative branch creates a law or changes a law, the executive branch has a responsibly to carry it out. It doesn’t say they have the responsibility to carry out a judicial law. And that’s something we need to talk about.”

Steve King



Like Cruz, Rep. Steve King (R-IA) has also introduced legislation prohibiting courts — including the Supreme Court — from considering the question of same-sex marriage, by taking on Article III of the Constitution.

“We could pass this bill before the Supreme Court could even hear the oral arguments, let alone bring a decision down in June,” King said when introducing the bill in early April. “That would stop it right then, there would be no decision coming out of the Supreme Court. This is a brake, and whether we can get the brake on or not between now and June, that we don’t know.”

Tom DeLay



In addition to signing the civil disobedience pledge, the former GOP House majority leader has advocated for states to ignore a Supreme Court ruling in favor of same-sex marriage.

“A ruling by the Supreme Court is nothing but an opinion if the legislative branch and the executive branch do not enforce it,” DeLay said on Newsmax TV’s The Steve Malzberg Show. “Not only that, if the states would just invoke the 10th Amendment and assert their sovereignty, they can defy a ruling by the Supreme Court. It’s in the Constitution. We can tell the court what cases they can hear.”

Texas State Rep. Cecil Bell



Texas Democrats thwarted a bill sponsored by Republican state Rep. Cecil Bell that would have prohibited state and local governments from recognizing, granting or enforcing same-sex marriage licenses. Nevertheless, when the statehouse was considering the bill, Bell was skeptical that a Supreme Court ruling would bring same-sex marriage to the state.

“If the Supreme Court sets a precedent that says same-sex marriage is a legal precedent that states should adhere, that states will suddenly flock to that precedent and begin to conform…the reality is that when the Supreme Court sets precedents, states don’t always adhere to them,” he told TPM at the time. “I am not predicting what Texas will do — but to assume that Texas will suddenly change how it does business is presumptuous.”

Alabama State Supreme Court Chief Justice Roy Moore



Alabama’s top judge can boast of the coveted accomplishment of having already defied the Supreme Court when it allowed same-sex marriage to become legal in his state. Right before a federal ruling striking down the state’s marriage ban was to take effect, state Chief Justice Roy Moore issued an order barring local probate judges from issuing same-sex marriage licenses.

“When federal courts start changing our Constitution by defining words that are not even there, like marriage, they’re going to do the same thing with family in the future,” he later said, doubling down on his order. “When a word’s not in the Constitution, clearly the powers of the Supreme Court do not allow them to redefine words and seize power.”