Portman, who was touted a potential running mate for Mitt Romney last year, says his son Will came out to his parents in February of 2011. That was about three months before Portman would see around 100 members the University of Michigan law school's graduating class walk out of his commencement speech in protest of his anti-gay record. That record includes a 2004 vote for a constitutional amendment banning gay marriage, and in 1999, support for a bill that would bar gay and lesbian couples from adopting.
Just this past election year, Portman was considered as one of the potential candidates to fill in Mitt Romney's vice-presidential pick and was naturally vetted by Romney's campaign team. According to the Columbus Dispatch's Jack Torry and Jessica Wahrman, Portman told Romney about his gay son, who didn't consider it an issue—although we went on to see Romney and Paul Ryan run on a platform that promised to defend DOMA and the idea of "a constitutional amendment defining marriage as a union between one man and one woman," as ABC News reported at the time. It's not known if Portman discussed the issue of same-sex marriage with Romney or, if he had been picked, if he would have backed those initiatives despite having a gay son.
In an op-ed with The Columbus Dispatch, Portman says his new decision was spurred by his 21-year-old son, who is a junior at Yale. He writes that his son helped him see that gay people don't choose to be gay:
Two years ago, my son Will, then a college freshman, told my wife, Jane, and me that he is gay. He said he’d known for some time, and that his sexual orientation wasn’t something he chose; it was simply a part of who he is. Jane and I were proud of him for his honesty and courage. We were surprised to learn he is gay but knew he was still the same person he’d always been. The only difference was that now we had a more complete picture of the son we love.
Portman adds that he's voicing his support for gay marriage now because the Supreme Court will be hearing arguments soon on California's Prop. 8, a state ban on same-sex marriage, as well as the constitutionality of the Defense of Marriage Act. According to The Advocate's Lucas Grindley, "He is now the only Republican currently in the Senate to support marriage equality, but he's not the only one in Congress. Florida Rep. Ileana Ros-Lehtinen, who has a transgender son, in 2011 became the first GOP congresswoman to support repeal of the Defense of Marriage Act."