A third Republican US Senator has come out in favour of equal marriage, following the lead of two others earlier this year.

Writing in an op-ed on Wednesday, Republican Senator Lisa Murkowski of Alaska on Wednesday announced her support for measures towards marriage equality.

Earlier this year, Senator Rob Portman who was among the original sponsors of the Defense of Marriage Act (DOMA) announced that he had changed his anti-equal marriage stance when his son came out as gay.

Following shortly afterwards, Senator Mark Kirk also came out in support.

“I am a life-long Republican because I believe in promoting freedom and limiting the reach of government,” Murkowski wrote.

“When government does act, I believe it should encourage family values.  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.”

The president of the Human Rights Campaign, a leading human rights organisation, commended the Alaskan Senator for coming out in support of equal marriage.

“We hope other fair-minded conservatives like Senator Murkowski stand up and join her,” HRC President Chad Griffin said in a statement.

“Alaska may be nicknamed ‘the Last Frontier,’ but we’ve got to make sure that LGBT Alaskans don’t have to wait to find justice.”

Murkowski previously described her views on equal marriage as “evolving”.

Cindy McCain, the wife of former GOP presidential nominee Senator John McCain, yesterday said she thought there would be a “major turn”, and that both major parties will support equal marriage by the next US presidential election.

Her husband, Senator McCain said in March that he didn’t think he would be following the lead of fellow Republican Senator Rob Portman.

Mrs McCain, however, said she thinks that her husband will eventually change his mind on the issue.