Pennsylvania Gov. Tom Corbett (R), in an interview with a local news station, compares gay marriage to marriage between siblings.

Corbett was responding to state attorneys fighting against gay marriage who likened it to marriage between 12-year olds, which is not allowed by state law because the law says marriage must be between a man and a woman.

"It was an inappropriate analogy," Corbett said. "I think a much better analogy would have been brother and sister, don't you?"

Corbett is rated by The Fix as the most vulnerable governor in the country. Recent polls have shown him to be very unpopular ahead of his 2014 reelection campaign.

Update 1:51 p.m.: Corbett has offered a semi-apology and an explanation. Here's his statement:

My words were not intended to offend anyone. If they did, I apologize. 

“I explained that current Pennsylvania statute delineates categories of individuals unable to obtain a marriage license. As an example, I cited siblings as one such category, which is clearly defined in state law. My intent was to provide an example of these categories. 

”The constitutional question is now before a federal court and that is the venue in which same-sex couples wishing to legally marry have standing to intervene and be heard. Same-sex marriage is an important issue and the question of its legal status is one that will be heard and decided upon its merits, with respect and compassion shown to all sides.” 

Update 1:45 p.m.: Corbett's potential Democratic opponents are now using his comments against him.

Rep. Allyson Schwartz (D-Pa.), meanwhile, is circulating a petition to denounce Corbett's comments and a web video.