The ad campaign is titled "One Thing" and emphasizes that Amendment 2 on the November ballot would only define marriage as the union of one man and one woman. Opponents of the measure have an ad campaign warning that the amendment would bring government intrusion into private lives of Floridians and might allow discrimination against unwed heterosexual couples who live together.

John Stemberger, the Orlando attorney who heads the Yes2Marriage.org campaign, said at a news conference that 27 states have defined marriage as a heterosexual union. He said "activist judges" in Massachusetts, California and Connecticut have changed the law and -- although the state has a "defense of marriage" statute -- a constitutional amendment is needed to prevent judges from doing that in Florida.

One advertisement features Alveda King, the niece of Dr. Martin Luther King Jr., saying that "everyone’s civil rights are safe" under Amendment 2. She warns voters, "Don’t be misled by dishonest advertisements" that say the amendment would affect everyone.

The other advertisement shows happy couples, churches and wedding scenes, with a voice saying marriage is an ancient institution that does not need changing.

Michael Kenny, deputy campaign manager for the opposition effort, said Florida Red & Blue will be running its own TV spots next week. He said there is no way of knowing how courts might interpret amendment language that bans not only gay marriage but any arrangement that is "the substantial equivalent" of a man-woman unit.

"An amendment worded like this has far-reaching consequences," he said. "It’s bad for our families, bad for the business community, bad for the universities and entire education system and has even been proved harmful to victims of domestic violence."