Which Republican Senator Will Support Gay Marriage Next? 5 to Watch

While Senate Democrats are rapidly accepting gay marriage—only seven holdouts remain—that's not the case for their Republican counterparts. Just two GOP senators have come out in support of same-sex marriage this year: Rob Portman of Ohio, who announced his support last month, and Mark Kirk of Illinois, who joined Portman on Tuesday.

But the lonely Portman-Kirk caucus could get some additions soon. Yes, foreseeing a change of positions on gay marriage can be difficult (see: Portman, a longtime opponent of gay marriage who changed positions after his son came out), and many Democratic lawmakers who have made the switch said it was a personal evolution, as well. That said, senators’ public statements, political situations back home, and personal experiences offer a few clues to who could evolve next.

Here are the five Republicans to watch:

MOST LIKELY

(Mark Thiessen/AP)

Lisa Murkowski of Alaska 

What she’s said: If there’s only one more Republican that flips, it’s probably going to be Murkowski. She told the Chugiak-Eagle River Star that her views are “evolving” but stopped short of endorsing gay marriage. "I think it's important to acknowledge that there is a change afoot in this country in terms of how marriage is viewed," she told the paper.

The political calculus: Murkowski indicated that where she falls on gay marriage could depend on where Alaskans stand. The state passed an amendment in 1998 that defines marriage as between a man and woman. But there are signs that it’s not political suicide to support gay marriage even in a heavily Republican state like Alaska. Her Democratic colleague, Sen. Mark Begich, has come out in favor of gay marriage, and he is up for reelection in 2014.

(J. Scott Applewhite/AP)

Susan Collins of Maine 

What she’s said: Collins has described herself as “a champion” of equal rights for gays and lesbians, the Associated Pressreports. The story goes on to say she doesn’t “openly” support gay marriage. When asked her stance on gay marriage, her office responded to National Journal by noting her votes in support of gay rights and that she voted against proposed constitutional amendments defining marriage. “She believes this matter is best left up to the states, which have traditionally handled family law," spokesman Kevin Kelley wrote. "Senator Collins will carefully follow the Supreme Court's consideration of this important issue."

The political calculus: Collins, a moderate Republican from a blue state, faces reelection in 2014. And although Democrats acknowledge beating Collins would be a tough task, not supporting gay marriage could provide Democrats with an opening for attack. She also doesn't have to fear an attack from the right, since conservatives in the state have yet to rally behind someone who could challenge her. In the end, the political benefits of supporting gay marriage outweigh potential harm.

POSSIBLY MAYBE

(AP Photo/J. Scott Applewhite)

Kelly Ayotte of New Hampshire 

What she’s said: In 2012, Ayotte said  that national Republicans should avoid discussing efforts in her state to repeal gay marriage because it takes the party off its economic message. She told New Hampshire’s WMUR last week that "I respect those who have changed their minds, but I believe in traditional marriage,” adding that she believes it’s an issue best left to the states. Ayotte has solid social-conservative bona fides: She gained prominence as attorney general when she represented New Hampshire in a Supreme Court case that upheld the state’s parental-notification law for abortion.

The political calculus: Ayotte is a New England Republican, and same-sex marriage is legal in the “Live Free or Die” state. She’s not up for reelection until 2016, so she doesn’t face much political pressure to change her position until closer to the election. But there are indications that pro-gay-marriage sentiments will only grow stronger in New Hampshire. A gay-marriage repeal effort failed last year in the state’s Republican-controlled Legislature.

THE LONG SHOTS

Pat Toomey of Pennsylvania 

What he’s said: Toomey made it clear that he supports defining marriage as between a man and a woman a week before Monday’s announcement that his Democratic colleague, Sen. Robert Casey, switched positions. His office released a statement saying Toomey “believes that the tradition of marriage is sacred and is best defined as between a man and a woman. He does realize that there are many Americans who feel strongly about this issue and support marriage for same-sex couples. The input of Pennsylvanians is therefore valued when Congress reviews legislation addressing same-sex marriage.”

The political calculus:Like the rest of the nation, public opinion on gay marriage has shifted dramatically in Democratic-leaning Pennsylvania. This year, 52 percent of Pennsylvania voters favored same-sex marriage, up from just 33 percent six years ago, according to a Franklin & Marshall College poll. Toomey doesn’t face reelection until 2016, so just like Ayotte, there is time to see whether gay-marriage support turns into a tide in Pennsylvania.

(Chet Susslin)

Ron Johnson of Wisconsin 

What he’s said: In a statement from his office to National Journal, Johnson said: "People have strong and deeply held opinions about marriage and family because they are central to our society. I believe that we should continue to leave it up to the people—acting through the states—to set guidelines. The federal government should not override the choices of any one community in an attempt to impose a national standard, but should respect the rights of the people and the states.” Johnson, known more as a fiscal than social conservative, has staked out a position that gay marriage is a states’-rights issue.

The political calculus:  Although Wisconsin backed President Obama twice, it also banned same-sex unions six years ago, 59 to 41 percent. But Wisconsinites just elected Democrat Tammy Baldwin last year, the first openly gay senator to serve in the Senate. Johnson’s up for reelection in 2016, and is considered one of the most vulnerable Republicans in his class.