The National Organization for Marriage (NOM) is calling for an investigation over a leaked list of contributors to the group's campaign supporting Proposition 8, the 2008 voter-approved amendment which overturned the California Supreme Court's ruling legalizing gay marriage in the state.

Gay rights advocate the Human Rights Campaign (HRC) last week released on its website a confidential 2008 IRS tax return listing 50 contributors to the campaign, including presidential hopeful Mitt Romney.

“It appears that someone with either the IRS or the HRC may have committed a federal crime by illegally obtaining and then releasing a confidential tax return of the National Organization for Marriage,” said NOM President Brian Brown in a statement. “It's clear that the tax return was stolen, either from NOM or from the government.”

HRC spokesperson Fred Sainz told gay weekly The Washington Blade that NOM, which is currently under fire for memos showing it wanted to pit minorities against gay marriage supporters, was attempting to change the conversation.

“It's the height of hypocrisy for NOM to claim others are violating the law – since NOM has flagrantly violated campaign finance and tax laws and is currently under investigation. NOM is clearly trying to change the conversation away from their unethical practices as well as the secret memos that we brought to light last week showing their ugly race-baiting tactics and their nondisclosure of a contribution from Governor Romney that was clearly meant for Prop 8.”