For the most part, the gay marriage debate now falls along partisan lines: Democrats support it, Republicans oppose.
But within the crowded field of likely 2016 presidential contenders, there's a lot of room for nuance. The would-be candidates have made much different arguments and have varying records on the issue.
Meantime, the issue continues to change. On Jan. 6, Florida became the second-largest state to recognize gay marriage, bringing the total to 36. And on Friday, the Supreme Court will meet privately to decide whether to consider cases that could lead to a more definitive ruling in favor of same-sex marriage.
Here's a look at what 16 major presidential contenders think, in order from most opposed to most supportive.
What he says: “I’m not a weathervane on this issue and I’m not going to change my position. I continue to believe that marriage is between a man and a woman.” (Washington Examiner)
What he's done: The governor of Louisiana backs a constitutional amendment to define marriage as between a man and a woman and supported a gay marriage ban as a member of Congress.
Where it stands in his state: Same-sex marriage remains illegal in Louisiana, but there is a pending appeal to the 5th Circuit Court of Appeals on a 2014 ruling that upheld Louisiana's ban.
What he says: “Texans spoke loud and clear by overwhelmingly voting to define marriage as a union between a man and a woman in our Constitution, and it is not the role of the federal government to overturn the will of our citizens.” (POLITICO)
What he's done: The Republican governor of Texas framed the marriage debate as a states' rights issue in the wake of a 2014 decision deeming Texas's ban unconstitutional.
Where it stands in his state: A state ban on same sex marriage was recently ruled unconstitutional, but the judge said it could continue to be enforced pending an appeal.
What he says: "If you look at other nations that have gone down the road towards gay marriage... It gets enforced against Christian pastors who decline to perform gay marriages, who speak out and preach biblical truths on marriage." (Huffington Post)
What he's done: The Republican senator from Texas introduced the State Marriage Defense Act in 2014, which would allow states to define marriage.
Where it stands in his state: A ban was ruled unconstitutional but is still in effect.
What he says: Marriage is “about a unity of men and women, for the purposes of having and raising children, and giving the child their birthright, which is to be raised by their natural mother and natural father." (Mediaite)
What he's done: The former Republican senator from Pennsylvania is such a well-known opponent of same-sex marriage that activists mounted a viral campaign to mar his Google search results.
Where it stands in his state: Same-sex marriage has been legal in Pennsylvania since May.
What he says: "Marriage is between a man and a woman. No group, be they gays, be they NAMBLA, be they people who believe in bestiality, it doesn't matter what they are. They don't get to change the definition." (Baltimore Sun)
What he's done: Carson is a surgeon, not a career politician, so he hasn't done anything yet.
Where it stands in his state: Same-sex marriage has been legal in Maryland since 2012.
What he says: On Republicans becoming more moderate on gay marriage: "If the Republicans want to lose guys like me and a whole bunch of still God-fearing, Bible-believing people, go ahead.” (MSNBC)
What he's done: The former Republican governor of Arkansas signed a law in 1997 banning gay marriage in the state. He's also called for impeachment of a judge who overturned the ban.
Where it stands in his state: A U.S. district judge ruled in November that the same-sex marriage ban in Arkansas is unconstitutional, but allowed the ban to continue pending appeal.
What he says: "There is a growing intolerance on this issue, intolerance of those who continue to support traditional marriage… Supporting the definition of marriage as one man and one woman, is not anti-gay. It is pro-traditional marriage.” (POLITICO)
What he's done: The Republican senator from Florida says that he believes states should handle marriage, not Congress.
Where it stands in his state: At midnight on Jan. 6, Florida became the 36th and second-largest state in the union to allow gay marriage.
Personally Against, But Politically Ambiguous
What he says: "It doesn't really matter what I think now. It's in the constitution." (Milwaukee Journal-Sentinel)
What he's done: As a Milwaukee County executive, Walker opposed efforts to provide health care benefits to gay partners of county employees. He was openly in favor of a 2006 constitutional amendment banning same-sex marriage, and opposed a law allowing gay couples to get certain county benefits.
Where it stands in his state: Same-sex marriage has been legal in Wisconsin since 2014, when the U.S. Supreme Court rejected appeals from Wisconsin and four other states seeking to keep their same-sex marriage bans.
What he says: “I don’t think there’s some referee who stands up and says, ‘OK, now it’s time for you to change your opinion,.' The country will resolve this over a period of time. But do I think it’s resolved? No.” (POLITICO)
What he's done: The Republican governor of New Jersey has long opposed gay marriage, vetoing a bill to legalize it in New Jersey in 2012. But in 2014 he dropped his appeal of the state Supreme Court judge's decision that the ban was unconstitutional.
Where it stands in his state: Same-sex marriage has been legal in New Jersey since 2014.
What he says: "I believe in old-fashioned traditional marriage but I don't really think the government needs to be too involved in this and I think the Republican Party can have people on both sides of the issue." (CNN)
What he's done: The Republican senator from Kentucky said the Supreme Court's 2013 decision to strike down a portion of the Defense of Marriage act was appropriate and that "as a country we can agree to disagree.” (ABC News)
Where it stands in his state: Same-sex marriage is banned in Kentucky.
What he says: "We live in a democracy, and regardless of our disagreements, we have to respect the rule of law. I hope that we can also 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." (The Washington Post)
What he's done: In 1994, during his first run for governor, Bush wrote an op-ed in the Miami Herald that said, "[Should] sodomy be elevated to the same constitutional status as race and religion? My answer is No,” reports Buzzfeed.
Where it stands in his state: Florida began recognizing same-sex marriage this month.
What he says: "I just think marriage is between a man and a woman, but if you want to have a civil union that's fine with me." (Huffington Post)
What he's done: The Republican governor of Ohio quickly walked back his civil union comment, saying he used the term "loosely." He has demonstrated support for an appeal of an upcoming ruling by a federal judge that will require Ohio to recognize same-sex marriages performed in other states where it is legal.
Where it stands in his state: Same-sex marriage is banned in Ohio.
What she says: “It really became very clear to me that if we're going to support marriage in our country, it should be available to everyone regardless of who they love and that this marriage equality issue is a great human rights issue." (Huffington Post)
What she's done: The former Secretary of State did not support gay marriage in her 2008 presidential campaign, but she issued a video announcing her support for it in 2013 after she left the State Department.
Where it stands in her state: Same-sex marriage has been legal in New York since 2011.
What he says: "All of us, wherever we happen to stand on the marriage equality issue, can agree that all our children deserve the opportunity to live in a loving, caring, committed, and stable home, protected equally under the law.” (Huffington Post)
What he's done: The Democratic governor of Maryland signed same sex marriage into law in his state in 2012, making it the eighth state to allow gay marriage.
Where it stands in his state: Same-sex marriage has been legal in Maryland since 2012.
What he says: On the Supreme Court's 2013 decision striking down the Defense of Marriage Act: "This is good news for all Americans who believe in the words carved in marble on the front of the Supreme Court building, equal justice under law." (Press release)
What he's done: The Democratic senator from Vermont voted against the anti-gay marriage Defense of Marriage Act in 1996, and voted no on a constitutional amendment against it in 2006.
Where it stands in his state: Same-sex marriage has been legal in Vermont since 2009.
What she says: "Marriage equality is morally right." (POLITICO)
What she's done: The Democratic senator from Massachusetts supported repealing the Defense of Marriage Act, parts of which the Supreme Court ruled unconstitutional in 2013.
Where it stands in her state: In 2004, Massachusetts became the first state to recognize same-sex marriage.