The National Organization for Marriage (NOM) on Wednesday announced it was considering whether to intervene in a federal case challenging Pennsylvania's ban on gay marriage.

With Wednesday's announcement that Pennsylvania Governor Tom Corbett – who has said he's personally opposed to marriage equality – would not pursue an appeal in the case, Pennsylvania became the 19th state, in addition to the District of Columbia, to allow gay couples to marry.

(Related: Pennsylvania Gov. Tom Corbett says he won't appeal gay marriage ruling.)

NOM President Brian Brown accused Corbett of “selling out his principles precisely when it is most necessary to stand by them!”

“Governor Corbett claims to be a man of principle and a supporter of marriage,” Brown wrote in a blog post. “But Governor Corbett is abandoning marriage with this choice.”

“The fact is that if Governor Corbett stood by the principles he claims, he'd have chosen to defend marriage to the very end,” Brown added. “The Supreme Court has indicated that they believe marriage should be left to the states and it is within states' rights to decide the matter. The Court very recently indicated as well a favorable view of the democratic role of the popular referendum process. In short, the challenge that the Governor is running away from today is one he most certainly could have won. So someone must step in and work to win.”