1) Sen. Mark Kirk (R-Ill.)
What he's said: "When I climbed the Capitol steps in January, I promised myself that I would return to the Senate with an open mind and greater respect for others. Same-sex couples should have the right to civil marriage. Our time on this Earth is limited, I know that better than most. Life comes down to who you love and who loves you back -- government has no place in the middle." (April 2, 2013)
What his announcement meant: Kirk, who recently returned to Congress after suffering a stroke, became just the second Senate Republican to come out in support of gay marriage, so his decision is a significant one that has and will generate lots of media attention. That said, Kirk's announcement shouldn't be seen as a sign that many more Senate Republicans will quickly follow suit because his profile is unique. Kirk's a moderate Republican with a history of working across the aisle -- an approach fueled by the fact that he comes from a deep blue state President Obama carried twice.
2) Sen. Rob Portman (R-Ohio)
What he's said: "I have come to believe that if two people are prepared to make a lifetime commitment to love and care for each other in good times and in bad, the government shouldn’t deny them the opportunity to get married." (March 15, 2013)
What his announcement meant: If Senate Republicans one day begin to move en masse toward endorsing gay marriage, look for the Ohio senator's name to be mentioned a lot. Portman became the first Senate Republican to support same-sex marriage, citing as his son's revelation that he is gay as the main reason he shifted his position. The senator was received warmly by gay rights advocates, but less hospitably by some social conservatives. Still, he remains a bedrock member of the party's Washington establishment and could well have real influence over how his colleagues approach the issue in the coming months and years.
3) Rep. Richard Hanna (R-N.Y.)
What he's said: "New York State allows all its citizens the freedom to marry the person they love. Under the Tenth Amendment, the federal government has a Constitutional responsibility to respect New York’s right to set its own laws. It’s my job to see that it does." (Dec. 21, 2012)
What his announcement meant: Hanna offered the above statement when he signed onto a measure to repeal the federal Defense of Marriage Act -- becoming just the second Republican to do so at the time. He offered explicit support for same-sex marriage on Feb. 25 when he signed a friend-of-the-court brief in the ongoing Supreme Court case over California's same-sex marriage ban. The brief argued that gay couples have the constitutional right to marry.
4) Rep. Ileana Ros-Lehtinen (R-Fla.)
What she's said: "I voted against the constitutional amendment defining marriage [in 2006] so I’m pleased to cosponsor the repeal of DOMA and work with my colleagues on marriage equality." (Sept. 23, 2011)
What her announcement meant: In 2011, the congresswoman became the first Republican co-sponsor of the attempt to repeal DOMA, setting her apart in the GOP conference. Like Hanna, Ros-Lehtinen also explicitly expressed her support for gay marriage when she signed the 2013 friend-of-the-court brief submitted for the Supreme Court case. (She earlier affirmed her support for gay marriage in a July 2012 interview.) Ros-Lehtinen's daughter, who came out as a transgender man, is an outspoken LGBT activist.