Sen. Lisa MurkowskiLisa MurkowskiOvernight Energy: Obama integrates climate change into national security planning GOP pressures Kerry on Russia's use of Iranian airbase Overnight Energy: Lawmakers kick off energy bill talks MORE (R-Alaska) on Wednesday became the third Republican in the upper chamber to back same-sex marriage.
"I am a life-long Republican because I believe in promoting freedom and limiting the reach of government. When government does act, I believe it should encourage family values," Murkowski said in a statement posted on her website.
"I support the right of all Americans to marry the person they love and choose because I believe doing so promotes both values: it keeps politicians out of the most private and personal aspects of peoples’ lives — while also encouraging more families to form and more adults to make a lifetime commitment to one another."
Sens. Mark KirkMark KirkFormer Miss Universe becomes surprise story to emerge from debate Senate rivals gear up for debates The Trail 2016: Trump seizes on Charlotte violence MORE (Ill.) and Rob PortmanRob PortmanGrassley accuses Reid of 'pure unfiltered partisanship' Senate passes funding bill to avoid shutdown Ryan optimistic about GOP majorities in House and Senate MORE (Ohio) are the two other Senate Republicans who have backed same-sex marriage. A dozen Democrats have made the same switch amid a broader shift in popular opinion.
Murkowski had hinted that she was moving toward supporting same-sex marriage, saying in March to a local Alaska newspaper that her views were "evolving."
"The term 'evolving view' has been perhaps overused, but I think it is an appropriate term for me to use," Murkowsi said at a local event according to the Chugiak-Eagle River Star.
Murkowski's announcement comes as the Supreme Court prepares to rule on the constitutionality of the Defense of Marriage Act and California's Proposition 8, which bans same-sex marriage in the state.
The pro-same sex marriage Human Rights Campaign praised Murkowski's move.
"Sen. Murkowski's courageous and principled announcement today sends a clear message that marriage equality must come to all 50 states in this country," HRC President Chad Griffin said in a statement.
"As the Supreme Court prepares to rule in two landmark marriage cases this month, a growing bipartisan coalition is standing up for the right of all couples to marry — and there is no turning back that tide."