By Yereth Rosen
ANCHORAGE, Alaska (Reuters) - U.S. Senator Lisa Murkowski of Alaska publicly backed gay marriage on Wednesday, becoming the third Republican senator to do so as she spoke out ahead of potentially landmark rulings from the Supreme Court on the issue.
Murkowski, 56, wrote in an essay posted on her Senate website that her decision was swayed, in part, by meeting a lesbian couple from Anchorage, one of whom was in the National Guard, who had adopted four children.
"This first-class Alaskan family still lives a second-class existence," Murkowski said in her essay.
Her announcement comes as the U.S. Supreme Court is expected to rule soon on a challenge to California's ban on gay marriage and a separate lawsuit targeting a provision of federal law that denies same-sex couples certain benefits.
She joins Republican Senators Rob Portman of Ohio and Mark Kirk of Illinois who earlier this year joined dozens of Democratic senators who support gay marriage. Twelve of the 50 U.S. states and the District of Columbia have legalized gay marriage.
Public opinion polls show a majority of Americans believe gay couples should have the right to wed, and Murkowski said in her essay that her decision was consistent with attitudes of "more and more Alaskans," especially the young.
She wrote that she had supported a 1998 amendment to the state constitution that defined marriage as solely a union between a man and a woman, but that her "thinking has evolved as America has witnessed a clear cultural shift."
"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," she said in her essay.
(For full essay see: http://www.murkowski.senate.gov/public/index.cfm?p=OpEds&ContentRecord_id=8295b7c7-e504-4b32-bc25-354b3aef41dc)
Murkowski is considered a moderate on many issues, a status that has caused her difficulties among other Republicans.
She had to mount a write-in campaign to win re-election in 2010 after being defeated in the Republican primary by Joe Miller, a more conservative candidate supported by Tea Party groups and by former Governor Sarah Palin.
In that campaign, Murkowski won strong backing from normally Democratic-leaning Alaska Natives and became the first person to win a Senate seat by write-in since 1954.
(Editing by Alex Dobuzinskis and Leslie Adler)