Brian Brown, president of the National Organization for Marriage (NOM), on Saturday reiterated his claim that allowing gay couples to marry will lead to polygamist marriages.

C-Span's Washington Journal hosted Brown and Sarah Warbelow, legal director at Human Rights Campaign (HRC), to discuss the issue.

On the program, Brown accused marriage equality supporters of denying rights to people in plural relationships.

“This is changing what marriage fundamentally is,” Brown said of marriage equality. “And if you talk about the change in the way that was brought up earlier, 'Well, this is about affirming people's rights. This is about affirming the dignity of their relationship,' then you have to ask a simple question: Why not three, four, or five people? Why is this only about same-sex marriage? Why do supporters of same-sex marriage now deny rights to those who want to practice polygamy?”

“Because once you change the fundamental truth that marriage is by definition the union of a man and a woman, all the other characteristics of marriage are up for grabs. And so I ask, why not, why not three, four or five?”

Later, Brown said that the Supreme Court would ultimately uphold state marriage bans.

“There is not a civil right to redefine marriage,” Brown said. “There is no right to do that. Again, the notion that the American people can't be trusted with certain questions and that our elites, our philosopher kings, get to decide these issues for us is fundamentally flawed. And I don't think it's going to end up winning out at the United States Supreme Court.”

For the record, Brown also predicted that the Supreme Court would uphold the Defense of Marriage Act (DOMA), which it struck down last year.