Republican Pennsylvania Gov. Tom Corbett, perhaps the nation's most vulnerable governor up for re-election next year, compared gay marriage to incest between a brother and sister, the Philadelphia Inquirer reports.

The governor was speaking about same-sex marriage on WHP-TV when one of the anchors asked about a statement administration lawyers had made in a court filing, comparing the marriage of gay couples to the marriage of children because neither can legally marry in the state.

“It was an inappropriate analogy, you know,” Corbett said, according to the Associated Press. “I think a much better analogy would have been brother and sister, don’t you?”

Pennsylvania is a state President Barack Obama won by 5 points in 2012, 52 percent to 47 percent.

Corbett won election in 2010 by an even larger margin, 54 percent to 46 percent. But according to a June Quinnipiac poll, the governor's approval rating stood at just 35 percent.