It's been a banner year for marriage equality.

The Supreme Court issued two landmark rulings in favor of same-sex marriage, one of which barred the government from denying benefits to gay couples; a number of Democratic lawmakers — and even a few Republicans — have "evolved" to support the issue; and three more states — Minnesota, Rhode Island, and Delaware — passed laws recognizing same-sex marriages, bringing the national total to 12 states. And now, New Mexico has suddenly become the new forefront in the nationwide push for marriage equality.

(Related: A timeline of America's evolution on gay marriage)

The same-sex marriage effort in New Mexico actually started back in 2004, when Sandoval County Clerk Victoria Dunlap decided to begin issuing marriage licenses to gay couples. Dunlap, realizing that the state had no law on the books restricting marriage — it remains the only state with no law recognizing or barring same-sex marriages or civil unions — issued 64 licenses to gay couples before the state's then-Attorney General Patricia Madrid demanded she halt that practice after just one day.

The issue went largely dormant until 2011, when a new attorney general, Gary King, issued an opinion saying the state would recognize same-sex marriages consummated by state counties or municipalities. King then went even further this year, writing in a briefing submitted to the state's Supreme Court that "New Mexico's guarantee of equal protection to its citizens demands that same-sex couples be permitted to enjoy the benefits of marriage in the same way and to the same extent as other New Mexico citizens."

With the state firmly behind same-sex marriage, the county clerk in Doña Ana County, Lynn Ellins, announced last week he would begin issuing marriage licenses to same-sex couples. His decision came on the heels of the New Mexico Supreme Court saying that it would not expedite a ruling on a gay marriage case.

Days later, a district judge ordered Santa Fe County, the state's third largest county, to begin issuing same-sex marriage licenses as well. And in another closely-watched case, the New Mexico Supreme Court also ruled last week that a photography studio had discriminated against a gay couple by refusing to shoot their wedding. In a unanimous ruling, the court said that action was "no different than refusing to photograph a wedding between people of different races."

Some two dozen Republican state legislators, led by Sen. William Sharer, have since said they will file a lawsuit to block Doña Ana County from issuing same-sex marriage licenses. That lawsuit would be moot if the state Supreme Court ultimately rules in favor of same-sex marriages, or if the New Mexico legislature decides to call for a ballot initiative on same-sex marriage to let voters decide the issue for themselves.

Last year, Maine, Maryland, and Washington all voted to approve gay marriages. Should such a measure come up in New Mexico, same-sex marriage proponents would likely have a built-in edge. A 2011 PPP survey found that a 45 percent plurality of New Mexico voters supported same-sex marriage. And almost 56 percent of voters there are projected to back same-sex marriage by 2016, according to an analysis by Nate Silver.