The Republican presidential candidate Rick Santorum said on Sunday the supreme court would not “have the final word” on same-sex marriage in the US, saying that instead it would be “important for Congress and the president, frankly, to push back when the supreme court gets it wrong”.

After the supreme court struck down the controversial Defense of Marriage Act (Doma) in June 2013, same-sex marriage has become legal in 37 states and the District of Columbia. The country’s highest court is due to decide the issue for good in a judgment expected to come down in June.

Nonetheless Santorum, a self-proclaimed “blue collar conservative” who polled strongly with evangelical voters in the 2012 primaries and was appearing on NBC, said: “I think it’s important to understand that the supreme court doesn’t have the final word. 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 was asked if he agreed with the former Arkansas governor Mike Huckabee, another Christian conservative and declared candidate for the 2016 GOP nomination, that on this issue the supreme court could be overruled by the states.

“I don’t advocate civil disobedience,” he said. “I do advocate the role of an informed citizen to try to overturn when a court makes a mistake and gets an issue wrong.

“I think the supreme court has as an equal branch of government the ability to overrule Congress and the president; they do it all the time,” the former US senator from Pennsylvania added. “But I also feel it’s the role of the Congress and the president to push back. It’s important that they be understood to be equal branches of government.”

Santorum outlined a situation, from his own experience in the Senate, in which legislation ruled unconstitutional by the supreme court could be altered and passed again, causing the court to reverse its opinion.

Asked if he would fight the supreme court in such a manner if it legalised same-sex marriage, he referred to the ruling which safeguards abortion rights in the US when he said: “Of course I’d fight it. Roe vs Wade was decided 30-something years ago [in fact 1973, 42 years ago] and I continue to fight it because the court got it wrong.

“And I think if the court decides this case in error I will continue to fight, as I have on the issue of life. That’s the role of a citizenry. We’re not bound by what nine people say in perpetuity.”

More than 60% of Americans now support the legalisation of same-sex marriage.