UNDATED (CNN) -- A one-time opponent of same-sex marriage has made a dramatic reversal. Prominent Ohio GOP senator Rob Portman announced the switch Thursday.
Portman says, "I'm announcing today a change of heart on an issue that a lot of people feel strongly about."
That issue, a controversial one, is whether gay couples should have the right to marry. And at the heart of Portman's reversal is a revelation from two years ago.
The senator describes as a moment of enlightenment, "Which is my son came to Jane, my wife, and I, told us that he was gay, and that it was not a choice, and that it's just part of who he is, and that's who he'd been that way for as long as he could remember."
His son, will came out to his parents while a freshman at Yale University, and soon after Portman was elected to the U.S. Senate. Portman says his reaction was, "Love. Support, you know, 110 % surprise. No idea."
Though never outspoken against gay marriage, the staunch conservative consistently voted against it.
He says his son's courage to come out launched a process for him to rethink his long-standing position, confiding in his faith and in his son's unique perspective. He says, "Talking to my pastor and other religious leaders and going through a process of, at the end, changing my position on the issue. But over time, yeah, we started talking about that more, and he was helpful as you can imagine at giving me some of his perspective on it and information about it, he's a very bright kid."
This is a change of heart from a very personal experience at a time when the volatile issue goes before the U.S. Supreme Court this spring.
Portman says he also talked with former Vice-President Dick Cheney, the highest-ranking Republican with an openly gay child, his daughter Mary.