Ohio Senator Rob Portman has been listed as a possible Republican vice presidential candidate in the past two presidential elections.
He doesn't think it will happen again in 2016.
Portman acknowledges that by coming out in support of gay marriage in March 2013 - after his son came out as gay - he may have doomed his chances of running for president or vice president.
'It puts me at odds with my party in many respects,' he said in an interview posted online this week with Hoover Institute fellow Peter Robinson.
'I believe it’s a conservative position. I never really thought deeply about it (before my son came to me). It seems to me to the extent that it’s not a choice, which is what believe. That is, Republicans ought to treat people as they are.'
While such a position by a Republican might seem refreshing to some, Portman realizes it may doom him in a party that has been staunchly against gay rights.
'It probably makes it difficult for me to win the primary election at a national election,' he said.
Portman was elected to the US Senate in 2010. He became the first incumbent statewide or national-level Republican to publicly support legal recognition of same-sex marriage since Lincoln Chafee in 2004.
Authors: Super User