(CNN) One day after the Supreme Court's historic same-sex marriage decision, Republican presidential candidates are still grappling with the ruling.

Texas Republican Sen. Ted Cruz called this week's two decisions from the Supreme Court "tragic" at a Saturday morning rally in Des Moines, Iowa.

"Yesterday, the court doubled down with a 5-4 opinion that undermines not just the definition of marriage, but the very foundations of our representative system of government," Cruz said. "For those who say the marriage decision yesterday is the law of the land, it is fundamentally illegitimate, it is wrong, it is not law, and it is not the Constitution."

The audience, holding American flags emblazoned with "Courageous Conservatives for Cruz," booed as Cruz said his 2016 rivals haven't responded forcefully enough to the decision.

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The first-in-the-nation caucus state has had legally recognized same-sex marriage since an Iowa Supreme Court decision in April 2009.

Meanwhile, at the Western Conservative Summit in Denver, candidates Mike Huckabee and Rick Perry had strong words for the Supreme Court.

Huckabee called the health care and same-sex marriage rulings "two of the most blatant, disturbing, disgusting examples of judicial activism in the history of these United States," adding that these decisions "(open) the door to something very dangerous to our way of life and our great republic."

The former Arkansas governor also attacked President Barack Obama, who came out in favor of same-sex marriage in 2012 after supporting civil unions for same-sex couples, for changing his views on marriage.

"He said that he believes that marriage is between a man and a woman, and he believed that, because he said as a Christian, it was the biblical view, and he had to believe that God was in the mix," Huckabee said. "One of three things is true: he was either lying in 2008, he's lying now, or God rewrote the bible and Barack Obama is the only one who got the new edition and I don't think that's what happened."

Rick Perry did not specifically criticize same-sex marriage, instead arguing that the decision should be made at the state level.

"One size will not fit all. That's not how this country was set up. This week the Supreme Court made decisions that, I'll be real honest with you, I didn't agree with at all," Perry said. "I have said from the get-go that these decisions, particularly that decision about traditional marriage, needed to be made in the states. I believe that with all my heart. That is where that needs to be decided."

Candidates such as Carly Fiorina and Jeb Bush, meanwhile, said it was time for the party to move on in wake of the decision.

Fiorina, the GOP's only female candidate, said she has "always been supportive of civil unions," but the Court's decision was "very different."

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"Throughout the millennia and in every religion in the world, marriage has a very specific meaning. Marriage is an institution, grounded in spirituality. It is the union of a man and a woman, and from that union comes life, and life is a gift from God," Fiorina said at the Western Conservative Summit. "Now that this decision has come down, I think we need to focus all of our energies on ensuring that we protect the religious liberties and the freedom of conscience of those who profoundly disagree with this decision."

In Nevada, Jeb Bush told reporters he didn't think that a legislative push by Republicans for constitutional amendment on same-sex marriage was realistic.

"I don't think it's going to happen. I think we ought to focus just as I said on trying to forge consensus so we can move forward," Bush said. "The courts have decided traditional marriage still is a hugely important element of a just, loving society and we should respect people that have long-term loving relationships and allow people to act on their conscience."

The candidates' comments were emblematic of an internal struggle in today's Republican Party on the rapidly growing acceptance nationwide of same-sex couples. As recently as 2004, President George W. Bush announced support for a federal constitutional amendment banning same-sex marriage, but polls taken over the past decade have revealed a surge in support for gay and lesbian nuptials, including among Republicans.