Sen. Lisa Murkowski of Alaska endorsed same-sex marriage Wednesday, making her the third Republican senator to switch positions on the issue.

In an op-ed published on her website, Murkowski, who backed a 1998 constitutional amendment banning same-sex marriage, said her evolution on the topic coincided with the thinking of "more and more Alaskans especially our younger generations."

"Fifteen years after that vote, I find that when one looks closer at the issue, you quickly realize that same-sex unions or civil marriages are consistent with the independent mindset of our state — and they deserve a hands-off approach from our federal policies," Murkowski wrote.

The announcement comes just days before the Supreme Court could weigh in on California's ban of gay marriage, known as Prop 8, or the federal Defense of Marriage Act. Murkowski joins Sens. Mark Kirk, of Illinois, and Rob Portman, of Ohio, as the only Republican senators publicly backing gay marriage.

Murkowski said her new position does not go against earlier stances she took as a lifelong Republican and Catholic. Instead, she said, it reaffirms her conservative principles.

Murkowski did add that churches should be able to define marriage as they choose.

"I am a life-long Republican because I believe in promoting freedom and limiting the reach of government," Murkowski said. "As a Catholic, I see marriage as a valued sacrament that exists exclusively between a man and a woman. Other faiths and belief systems feel differently about this issue - and they have every right to."