Republican presidential candidate Donald Trump addresses a campaign rally in Clinton, Iowa on Saturday. (Charles Ommanney/The Washington Post)

Donald Trump criticized the Supreme Court decision legalizing same-sex marriage and said he would "strongly consider" appointing judges inclined to overrule it if he is elected president.

"I don't like the way they ruled," Trump said on "Fox News Sunday." "I disagree with the Supreme Court from the standpoint that it should be a states' rights issue and that's the way it should have been ruled on ... I would have much preferred that they ruled at a state level and let the states make those rulings themselves."

With one day left before the Iowa caucuses, Trump said he was "very honored" to have support from evangelicals in Iowa and took pains to compliment the socially conservative voting bloc that will shape the outcome for Republican candidates.

"We've had tremendous support from ministers, pastors, Christians generally, evangelicals," Trump said. He called his endorsement from Jerry Falwell, Jr., the president of Liberty University, a "very big turning point" in the primary race.

Trump is entering Monday's first-in-the-nation primary contest with an apparent lead in the polls. The latest Des Moines Register/Bloomberg survey released Saturday night found him in first place with 28 percent, followed by Sen. Ted Cruz (R-Texas) with 23 percent and Sen. Marco Rubio (R-Fla.) with 15 percent.

Keeping up his attacks on Cruz, Trump slammed the Texas senator for failing to disclose loans from Goldman Sachs and Citibank to his 2012 Senate campaign and for having been born in Canada, "which probably makes it so he might not be able to run."

"He didn't know he was a citizen of Canada until 15 months ago," Trump said. "Give me a break."

Still, Trump played down the idea he has to win Iowa in order to eventually win the GOP presidential nomination.

"No, I don't have to win it,” Trump said in an interview on CBS’s “Face the Nation."

"I think it would be really good to win Iowa. I'd like to win Iowa. I'm doing really well with the evangelicals in Iowa. But I'm also doing tremendously well all over the country with the evangelicals. I'm leading by a lot."

Trump sought to defend himself from allegations that he will not side with social conservatives if elected to the White House, given his inclination toward social liberalism in the past.

"If I'm elected, I would be very strong in putting certain judges on the bench that I think maybe could change things," Trump said on Fox of the same-sex marriage decision.

"I can see changes coming down the line, frankly," he said.