The Supreme Court hears arguments Tuesday about whether same-sex couples have the constitutional right to marry, and this has thrust the issue back into the spotlight - and the 2016 presidential campaign.
A February CBS News poll found that 60 percent of Americans say it should be legal for same-sex couples to marry. That's up from 46 percent in November 2012, and the percentage of people who believe it should not be legal has dropped to 35 percent today from 41 percent on November 2012.
But the Republicans running for president or who are expected to run say they still support the view that a marriage should be between a man and a woman. Some have taken a milder tone and say that they would attend the wedding of a friend or family member who was gay, even if they didn't believe they should be getting married.
Democrats, on the other hand, are more likely to have embraced marriage for gay and lesbian couples.
Marco Rubio: Sexual preference is not a “choice,” but same-sex marriage is not a right
"It's not that I'm against gay marriage. I believe the definition of the institution of marriage should be between one man and one woman," Marco Rubio, Florida's Republican senator and a 2016 candidate, said in an interview on CBS' "Face the Nation." "States have always regulated marriage. And if a state wants to have a different definition, you should petition the state legislature and have a political debate. I don't think courts should be making that decision."
"I don't believe same-sex marriage is a Constitutional right," Rubio added. "I also don't believe that your sexual preferences are a choice for the vast and enormous majority of people. In fact...I believe that sexual preference is something that people are born with."
Rubio set off questions for his fellow Republicans earlier this month after he said in an interview with Fusion's Jorge Ramos that he would attend the same-sex wedding of a gay family member or staffer even if he might "disagree with a choice they've made."
Ted Cruz: Legislate for one man, one woman
Last week, Sen. Ted Cruz, R-Texas, filed two bills that he said will protect the right of the American people to define marriage as a union between a man and a woman. The Restoration of Marriage Amendment would guarantee that the U.S. and each state and territory have the right to define marriage as the union of one man and one woman (and free states of the obligation to recognize different unions performed in other states), while the Protect Marriage from the Courts Act of 2015 would prevent federal courts from ruling on state marriage laws.
"The people should decide the issue of marriage, not the courts," Cruz, who is also a candidate for the GOP nomination, said in a statement. "The union of a man and a woman has been the building block of society since the dawn of history, and the people in numerous states have repeatedly affirmed that truth in their laws. Nothing in the Constitution prohibits that." It's a stance he proudly reaffirmed while speaking to the Iowa Faith and Freedom Coalition over the weekend.
But Cruz has no issue with speaking to people who may feel differently. Last week, two gay hotel owners came under fire from the gay community after they hosted a dinner for Cruz in their Manhattan apartment.
As for attending a gay wedding? Cruz dodged the question on conservative radio host Hugh Hewitt's show earlier this month, saying none of his loved ones have had one so he hasn't faced that particular situation.
Rand Paul: Treat people fairly under the law
Kentucky senator and 2016 GOP candidate Rand Paul has said he believes marriage is an institution for one man and one woman, but the depth of those views has shifted. In late March, he reportedly told a group of pastors that there was a "moral crisis that allows people to think there would be some other sort of marriage."
On the other hand, there was a CNN interview earlier this month in which he argued that, "people ought to be treated fairly under the law." He also said, "You could have both traditional marriage, which I believe in. And then you could also have the neutrality of the law that allows people to have contracts with another."
Jeb Bush: Respect the rule of law
Former Florida Gov. Jeb Bush has not taken as hard line as some of his colleagues, suggesting he might be open to some form of legal protection for gay couples that stops short of marriage.
"We live in a democracy, and regardless of our disagreements, we have to respect the rule of law. I hope that we can show respect for the good people on all sides of the gay and lesbian marriage issue -- including couples making lifetime commitments to each other who are seeking greater legal protections and those of us who believe marriage is a sacrament and want to safeguard religious liberty," Bush said in January.
He has backed the idea that it should be a state decision, but has said that states should respect the law when it is overturned by the courts. And he told Charlie Rose in 2012 that gay parents "should be held up as an example to others" if they "love their children with all their heart and soul and that's what they do and that's how they organize their life."
His stance now has evolved since he ran for governor in 1994, when he wrote in a Miami Herald op-ed, "[Should] sodomy be elevated to the same constitutional status as race and religion? My answer is No." He was arguing that people who are gay did not deserve special legal protection.
Scott Walker: I've been to a same-sex wedding reception
For Wisconsin Gov. Scott Walker, a gay wedding is not a hypothetical question: He told reporters in New Hampshire earlier this month that he's been to a wedding reception for a gay member of his family, even though he believes marriage is defined as the union between a man and a woman.
Walker supported a 2006 constitutional amendment in Wisconsin prohibiting same-sex marriage, but the ban was struck down by a federal judge in 2014. Lately, he has been quieter on the issue, suggesting it's out of his hands for now. But speaking to the Iowa Faith and Freedom Coalition Saturday, he reiterated his belief that marriage is defined as one man and one woman and states should have the right to define it.
Chris Christie: Can't change New Jersey's preferences
New Jersey Gov. Chris Christie hails from a state where a majority of voters support legalizing same-sex marriage. But he still surprised some people by dropping a legal battle over same-sex marriage in the state in 2013, making New Jersey the first state to legalize those unions after the Supreme Court struck down the Defense of Marriage Act that June.
Like many of his colleagues, however, he believes defining marriage should be left to the states and doesn't think opponents should stop fighting it. He personally does not believe in same-sex marriage.
Rick Santorum: Same-sex wedding "a violation of my faith"
Former Pennsylvania Sen. Rick Santorum became a target of gay activist Dan Savage in 2003 after equating gay sex with practices like bestiality and polygamy, resulting in an internet campaign to give his last name a new, crude definition. But that has never convinced Santorum, who ran for president in 2012, to back down on the issue. He told conservative radio host Hugh Hewitt that he would not attend a gay wedding, because it would be "a violation of my faith."
Ahead of the Supreme Court's decision, Santorum's faith-based film production company, Echolight, helped produce a video warning that religious freedom would be at risk if the court rules that same-sex marriage is a constitutional right. It was distributed by the Family Research Council for pastors to play in their churches.
Bobby Jindal: My views are "not evolving"
Louisiana Gov. Bobby Jindal is one of the potential 2016 candidates for the GOP nomination who has said he would attend a same-sex wedding of someone he loved and cared for even though he believes marriage is limited to a man and a woman. And his views, he said at the Iowa Faith and Freedom Summit over the weekend, are "not evolving."
Jindal has also warned about an attack on religious liberty and has bashed the opponents of controversial religious freedom laws that have been passed in some states. He has promised to fight for a such a law in Louisiana, although he insists it does not allow people to refuse service to gay or lesbian individuals.
Rick Perry: Other issues are more important
Would former Texas Gov. Rick Perry attend a same-sex wedding? "Probably," the 2012 Republican presidential candidate told conservative radio host Hugh Hewitt last week. But he also thinks people should be talking about issues like the economy and national defense - not marriage.
"If you're not really not talking about those two on a regular basis and coming up with solutions on how to get this country back working, how to get this debt under control, and how to put America back into a position of being respected by our allies and being an influence in the world, then you're spending some time that frankly doesn't need to be spent on some issues that are secondary or tertiary to the future of this country," he said.
Mike Huckabee: The GOP should oppose same-sex marriage
Mike Huckabee, the former governor of Arkansas and a former pastor, has used a variety of analogies to describe his opposition to same-sex marriage. In 2010, he said allowing gays and lesbians to wed would be like legalizing incest, polygamy or drug use. Earlier this year, he likened being gay to drinking or using profanity.
While he believes that there is room in the Republican Party for those who support same-sex marriage, he hopes the party doesn't change its view.
"Unless, you know, I get a new version of the scriptures, it's really not my place to say, OK, I'm just going to evolve," he explained. "It's like asking somebody who's Jewish to start serving bacon-wrapped shrimp in their deli. We don't want to do that. I mean, we're not going to do that. Or asking a Muslim to serve up something that is offensive to him or to have dogs in his backyard."
Hillary Clinton: A long history with the issue
Since her husband, former President Bill Clinton, signed the Defense of Marriage Act in 1996, Clinton has held just about every view on the spectrum of same-sex marriage. In 2000, she said she believed it was for a man and a woman. For a while, she advocated it was a state decision. And in 2015, the video she released to announce her presidential bid featured a gay couple. Her campaign staff says she supports same-sex marriage and wants the Supreme Court to rule that it is a constitutional right.
The long history has left her a bit touchy when it comes to the subject of marriage. During a 2014 interview on NPR, she took issue with the suggestion that her views had evolved for political reasons.
"Somebody is always out front and thank goodness they are. But that doesn't mean that those who join later -- in being publically supportive or even privately accepting that there needs to be change -- are any less committed," she said when the host, Terry Gross, noted that there were many supporters of same-sex marriage in the 1990s when Clinton still opposed it.
"I think you are trying to say that I used to be opposed and now I am in favor and I did it for political reasons. And that's just flat wrong. So let me just state what I feel like I think you are implying and repudiate it. I have a strong record. I have a great commitment to this issue and I am proud of what I've done and the progress were making," she said.
Martin O'Malley: It's a human right
Former Maryland Gov. Martin O'Malley is likely to bring up his support for same-sex marriage every time he talks to fellow Democrats. "The dignity of every person tells us that the right to marry is not a state right, it is a human right," he said at a Democratic event in Polk County earlier this month.
It's not just a statement about his own position on the issue; it was a subtle jab at potential rivals like Clinton, who haven't always espoused that view.
While O'Malley was governor, he signed a law legalizing same-sex marriages that was later reaffirmed through a state referendum.
Jim Webb: Country's evolution "a good thing"
Like Clinton, former Virginia Sen. Jim Webb has spanned the spectrum of opinions on same-sex marriage. As a Senate candidate in 2006, he said it was between a man and a woman but didn't support the idea of a constitutional amendment saying so. In 2014, he said on NBC that the country's "evolution" on the issue has "been a good thing."