Floridians voted Tuesday night to amend the state's constitution to prohibit gay marriage.
The amendment received more than the 60 percent of the votes it needed.
Florida law already bans gay marriage but Amendment 2 supporters said a constitutional ban was needed in case a judge overturned those laws.
"It was a long, hard fight," said John Stemberger, chairman of the pro-Amendment 2 campaign. "The ramifications are huge. It shows that the vast majority of people in Florida support marriage as between a man and a woman ... and they did not buy the scare tactics put forward by" amendment opponents.
Those opponents argued that the amendment was so broadly and vaguely worded that it would also block the legal rights of couples in domestic partnerships.
Supporters of the Marriage Protection Act, as the amendment was called, said it is narrowly focused on defining marriage as the union of one man and one woman. It also invalidates any "legal union that is treated as marriage or the substantial equivalent thereof." But that clause was meant to prevent Florida from adopting civil unions, as Vermont has, said Mathew Staver, dean of the Liberty University School of Law.
The amendment would have no effect on domestic partnership because they are not the "substantial equivalent" of marriage, he said.
Derek Newton, manager of the anti-Amendment 2 campaign, was skeptical. "We'll just have to hope they don't do what they've done in other states" that have passed same-sex marriage bans. "They say they won't go after domestic partnerships, then as soon as the amendments pass they go to court to challenge those rights."