Concord, N.H. --

Whether they like it or not, Republican presidential candidates are joining New Hampshire's intensifying same-sex marriage debate.

State lawmakers plan to take up a measure to repeal the law allowing same-sex couples to wed, and a vote is expected in January - the month New Hampshire holds the nation's first Republican presidential primary contest.

The impending focus on same-sex marriage carries risk for several White House contenders - including former Massachusetts Gov. Mitt Romney, Texas Gov. Rick Perry and former businessman Herman Cain - whose inconsistencies on the topic are well documented. The GOP candidates' increasingly vocal support for traditional marriage also threatens to alienate a growing number of younger Republicans and independents.

The Republican candidates aren't shying away from the topic as they run for the nomination of a GOP dominated by conservatives and pushed further to the right by the Tea Party over the past few years.

"As conservatives, we believe in the sanctity of life, we believe in the sanctity of traditional marriage, and I applaud those legislators in New Hampshire who are working to defend marriage between one man and one woman," Perry told a New Hampshire audience recently.

Romney's reversal

Romney was the Massachusetts governor when his state legalized same-sex marriage. The Romney administration, as directed by the courts, granted almost 200 same-sex marriage requests for gay and lesbian couples in 2005.

Campaign spokesman Ryan Williams said the ex-governor had little choice but to follow the state Supreme Court ruling at the time. He noted his candidate's consistent opposition to both same-sex civil unions and marriages, adding that Romney supports the New Hampshire repeal effort.

But Romney has reversed himself on whether same-sex marriage should be addressed at the state or federal level. He now favors a federal constitutional amendment banning the practice. But as a Massachusetts Senate candidate in 1994, Romney told a Boston-area gay newspaper that same-sex marriage is "a state issue."

Both Perry and Cain have drawn conservative criticism for recent comments related to same-sex marriage.

Asked in mid-October whether he supports a federal marriage amendment, Cain told the Christian Broadcasting Network that federal legislation is necessary to protect traditional marriage. That seemed to be a direct contradiction from his statement of just six days earlier, when he told "Meet the Press" host David Gregory that states should be allowed to make up their own minds.

In Perry's case, the Texas governor says he supports the New Hampshire repeal. But in July, he said that New York's move to legalize same-sex marriage was "fine by me." A week later, facing criticism, he took back the comments. "It's fine with me that the state is using their sovereign right to decide an issue. Obviously gay marriage is not fine with me," he said.

Gingrich's connection

Former House Speaker Newt Gingrich has another problem.

Earlier in the fall, he told Iowa spectators that same-sex marriage is a "temporary aberration" likely to go away because it defies convention. Gingrich, who has been married three times, has a half sister in a same-sex marriage.

"The truth is that you're living in a world that no longer exists," Candace Gingrich-Jones wrote the former speaker in a letter posted on the Huffington Post in 2008: "In other words, stop being a hater, big bro."