The Southern Poverty Law Center this week labeled as "hate groups" several political and religious organizations that campaign against same-sex marriage and, the center says, engage in "repeated, groundless name-calling" against gays and lesbians.

Included on the list released by the civil rights organization is the Family Research Council, a prominent and politically influential group of social conservatives. The report by the law center, which has spent four decades tracking extremist groups and hate speech, accuses the council and a dozen other groups of putting out "demonizing propaganda aimed at homosexuals and other sexual minorities."

The report, which has sparked debate across the Internet, taps into the continuing potency of social issues, such as same-sex marriage, in American politics. Several of the groups described in the report supported a successful effort to oust state Supreme Court judges in Iowa because of a unanimous ruling last year that legalized same-sex unions.

The Family Research Council has been at the forefront of political activism against same-sex marriage. In explaining the decision to put the council on its hate-groups list, the law center highlighted comments by Peter Sprigg, a senior fellow for policy studies at the council, who told MSNBC host Chris Matthews this year that he thinks "homosexual behavior" should be outlawed.

Council President Tony Perkins, who was also named in the report, called the hate-group designation a political attack by a "liberal organization."

"The left's smear campaign of conservatives is . . . being driven by the clear evidence that the American public is losing patience with their radical policy agenda as seen in the recent election and in the fact that every state . . . that has had the opportunity to defend the natural definition of marriage has done so," Perkins said in a statement.

"Earlier this month, voters in Iowa sent a powerful message when they removed three Supreme Court justices who imposed same-sex marriage on the state. Would the SPLC also smear the good people of Iowa?"

The law center said it chose to highlight the groups on the list "based on their propagation of known falsehoods" and "repeated, groundless name-calling."

"Viewing homosexuality as unbiblical does not qualify organizations for listing as hate groups," the report said.

The debate over the list has focused on whether the law center is right to equate anti-gay views with racism.

Dan Savage, a gay rights advocate and columnist, said in an interview on CNN that "we need a cultural reckoning around gay and lesbian issues. There was once two sides to the race debate. There was once a side, you could go on television and argue for segregation, you could argue against interracial marriage, against the Civil Rights Act, against extending voting rights to African Americans, and that used to be treated as one side . . . of a pressing national debate, and it isn't anymore. And we really need to reach that point with gay and lesbian issues. There are no 'two sides' to the issues about gay and lesbian rights."

Brian Brown, president of the National Organization for Marriage, objected to his organization's inclusion in the center's report and said the notion that groups opposed to same-sex marriage are equivalent to racists is wrong.

"This is about protecting marriage. This isn't about being anti-anyone," Brown said. "The whole idea that somehow those folks who stand up for traditional marriage, like the Family Research Council, are hateful is wrong. [The law center is] trying to marginalize and intimidate folks for standing up for marriage and also trying to equate them somehow to the KKK."