The Human Rights Campaign (HRC) has dropped the equality rating of a law firm over partner Cleta Mitchell's repping of anti-gay marriage group the National Organization for Marriage (NOM).

Mitchell, a partner at D.C.-based Foley and Lardner, will lobby on behalf of NOM in Minnesota, the Minnesota Independent reported. Mitchell registered as a lobbyist at the Minnesota Campaign Finance and Public Disclosure Board and is expected to lobby the board on behalf of NOM, which is keen on avoiding disclosure of its donors as it campaigns for a proposed constitutional amendment that would ban gay marriage in Minnesota.

On Tuesday, HRC, the nation's largest gay rights group, informed the law firm that it would no longer be recognized as a gay-friendly employer.

“In a time when major corporations, including the nation's top law firms, are taking unprecedented strides in support of LGBT equality with regards to their workplace practices and business activities, your firm has regrettably taken a notable step backwards,” HRC wrote in a letter to CEO Jay Rothman. “In the 2010 [Corporate Equality Index], Foley & Lardner achieved a perfect 100 score. In the 2012 CEI to be released next month, your firm will drop further to a 60, one of the lowest scores earned by an Am Law firm in the upcoming report.”

Earlier this year, gay GOP group GOProud Chairman Chris Barron got into hot water after he called Mitchell a “nasty bigot” during an interview.