Elizabeth Edwards says the idea that gay marriage threatens heterosexual marriage is "complete nonsense."
Edwards reiterated her support during a speech in Sacramento, saying she thinks there's an "undue fear of gay marriage."
As she campaigns for her husband John's presidential campaign in California, Elizabeth Edwards has staked out an independent position on gay rights.
She appeared last month at a breakfast before San Francisco's gay pride parade, where she announced her support for gay marriage.
The next day, John Edwards, a Democrat, said his wife's position surprised even him. The former North Carolina Senator opposes gay marriage but supports civil unions.