By Sarah N. Lynch and Kim Palmer
WASHINGTON/CLEVELAND (Reuters) - Senator Rob Portman became the most prominent Republican lawmaker to back gay rights when he reversed his opposition to same-sex marriage on Friday, two years after his son told him he was gay.
In a newspaper opinion piece on Friday, shortly before the Supreme Court is to hear arguments in two key cases on the issue, the Ohio senator said he now supports gay marriage.
"I have come to believe that if two people are prepared to make a lifetime commitment to love and care for each other in good times and in bad, the government shouldn't deny them the opportunity to get married," Portman wrote in an op-ed piece in Ohio's Columbus Dispatch.
"That isn't how I've always felt. As a Congressman, and more recently as a Senator, I opposed marriage for same-sex couples. Then, something happened that led me to think through my position in a much deeper way."
Portman's 21-year-old son, Will, told the senator and his wife in February 2011 that he was gay and had been "since he could remember."
It was the latest show of public support for gay rights. President Barack Obama announced last year that he approved of gay marriage, and in his inaugural speech in January, he equated gay rights with civil rights.
The Supreme Court hears oral arguments later this month in two cases related to gay marriage. One challenges the 1996 federal Defense of Marriage Act, which defines marriage as a union between a man and a woman. In a related case, the court will also hear arguments that question a California law, known as Proposition 8, banning gay marriage.
Portman was quoted by the Cleveland Plain Dealer newspaper as saying he now believes same-sex couples who marry in states where it is legal should be eligible for the same federal benefits granted to heterosexual couples.
Portman served as trade representative and then White House budget director under former President George W. Bush.
He was among the front-runners to be Mitt Romney's vice presidential pick during the 2012 election, but budget hawk Representative Paul Ryan of Wisconsin eventually got the nod.
The Republican Party has become increasingly split on the gay marriage issue, with some arguing that socially conservative positions such as opposition to same-sex marriage are contributing to the party's election losses.
An early Republican favorite for the 2016 presidential race, Senator Marco Rubio of Florida, staged a defense of traditional marriage in a high-profile speech to a conservative conference on Thursday.
"Just because I believe that states should have the right to define marriage in the traditional way does not make me a bigot," the 41-year-old Cuban-American told the Conservative Political Action Conference.
But Republican strategist John Feehery said Portman's announcement could change attitudes in the party.
"I think so. The fact of the matter is Dick Cheney has been out there on this. Ted Olson, Rob Portman. And what's becoming clear is if you know somebody who happens to be gay, you feel much differently about this issue. The fact is we all know somebody who is gay. So I think this is going to be another indication that times are changing on this issue." he said.
In his op-ed piece, Portman wrote of how he has "wrestled" with reconciling his Christian faith with the desire for his son to have the same opportunities as his siblings.
"Ultimately, for me, it came down to the Bible's overarching themes of love and compassion and my belief that we are all children of God," he said.
Keith Cottrell, 40, an IT professional who lives in Cleveland, said he didn't "see much nobility" in Portman's decision because he only lined up behind gay rights after learning of his son's sexuality.
"I mean I'll gladly take his vote but would we applaud someone who constantly voted against women's rights if they changed their mind after having a daughter?" Cottrell said.
Portman said he consulted clergy members and friends including former Vice President Dick Cheney. Cheney, who has an openly gay daughter, has reiterated his support for gay marriage over the past several years, despite his deeply conservative views on many issues.
Bob Vander Plaats, president of the Family Leader, an influential group of social conservatives in Iowa, said Portman had been "short-sighted" for changing his views.
"I don't see the Republican Party any time soon abandoning his stance on marriage. I see more than anything it is emboldened in their stance on marriage," he said. "The last time I checked, God's word was the same yesterday, today, and tomorrow," he said.
Portman's new position was supported by former opponent David Axelrod, who was Obama's senior campaign advisor.
"Courageous decision by Rob Portman to endorse same-sex marriage, guided by the love of a parent rather than by party ideology," Axelrod tweeted.
(Additional reporting by Alistair Bell and Samuel P. Jacobs; Editing by Vicki Allen and Bernadette Baum)