Brian Brown, president of the National Organization for Marriage (NOM), on Monday expressed disappointment over New Jersey Governor Chris Christie's decision to withdraw an appeal to a ruling legalizing gay marriage in the state.

Christie, a Republican who has said that he supports the state's civil unions law but not marriage for gay couples, dropped the appeal as gay couples began marrying on Monday after the state Supreme Court refused to delay the lower court's ruling.

(Related: Chris Christie drops gay marriage appeal.)

“There's no question that the courts of New Jersey are responsible for the imposition of same-sex marriage in that state, and we sharply criticize them for redefining our most important social institution with no regard to the wishes of voters or even elected officials,” Brown wrote in a blog post. “The refusal of the New Jersey Supreme Court to order a stay of the same-sex 'marriage' ruling was wrong, and the latest example of an activist judiciary running amok, substituting their views for those of the people of the state. Still, we are extremely disappointed in Governor Chris Christie for withdrawing the state's appeal of the underlying decision, effectively throwing in the towel on marriage. The mark of a leader is to walk a principled walk no matter the difficulty of the path. Chris Christie has failed the test, abandoning both voters and the core institution of society – marriage as the union of one man and one woman.”

Brown added that the decision would sink Christie's presidential aspirations.

“Regrettably, Governor Christie's decision to surrender on marriage reveals him to be a man who lacks the courage of his supposed convictions,” Brown said. “As far as we are concerned, it's a disqualifying failure. His surrender on marriage effectively surrenders any chance he might have had to secure the GOP nomination for president.”