Seven GOP candidates – Ron Paul, Herman Cain, Rick Perry, Mitt Romney, Michele Bachmann, Newt Gingrich and Rick Santorum – are among those being urged to boycott this weekend's Values Voter Summit because its sponsors are anti-gay.

“The Family Research Council (FRC) and the American Family Association (AFA) are among the chief purveyors of lies about the LGBT community – lies that stoke hate and violence,” said Mark Potok, director of the Southern Poverty Law Center's (SPLC) Intelligence Report. “LGBT people are now, by far, the group most victimized by violent hate crimes in America. Public figures should not lend their names to groups that vilify them.”

The SPLC publicly called on the candidates to avoid the event in an ad published Friday in The Washington Post.

Under the headline, “Just whose values are represented at the Values Voter Summit?,” the AFA is quoted as saying, “The homosexual agenda represents a clear and present danger to virtually every fundamental right given to us by our Creator and enshrined for us in the Constitution,” and, “Homosexuality gave us Adolph Hitler, and homosexuals in the military gave us the Brown Shirts, the Nazi war machine and six million dead Jews.” The FRC is quoted as saying, “I think there would be a place for criminal sanctions against homosexual behavior,” and, “Every special 'right' or concession we make to the homosexual community Christians pay for in freedom.”

“Our criticism of these groups has nothing whatsoever to do with their opposition to same-sex marriage or their belief that the Bible describes homosexuality as a sin,” Potok added. “Rather, it's based entirely on their continuing use of discredited research and outrageous falsehoods to defame the LGBT community.”

Scheduled to appear at the three-day event on Friday are Minnesota Rep. Michele Bachmann, former Godfather's Pizza CEO Herman Cain, former House Speaker Newt Gingrich, former Pennsylvania Senator Rick Santorum and Texas Governor Rick Perry. Texas Rep. Ron Paul is expected to address the crowd on Saturday.

House Speaker John Boehner and Brian Brown, the president of the National Organization for Marriage (NOM), the nation's most vociferous opponent of gay marriage, are also scheduled to attend the event.