The National Organization for Marriage, which backed California's Proposition 8 -- a referendum that outlawed same-sex marriage in the state but was eventually ruled unconstitutional -- is fighting the state's transgender law, the Los Angeles Times reported.
Brian Brown, president of the organization, has called on members to join a signature-gathering effort to have a repeal measure put on California's November 2014 ballot.
Brown has called the transgender law "a horrible attempt by activists to strip society of all gender roles."
"NOM has long warned that when marriage is redefined, other important social norms are soon destroyed," the group said on its website.
Shannon Minter, legal director of the National Center for Lesbian Rights, said repealing the law would not stop the state from protecting transgender students.
"The organizations promoting a referendum are nothing more than hate groups, and their attempts to target and demonize a vulnerable group of children are shameful," Minter said. "There is no place for these hate groups in our state."