MIAMI -- A federal judge on Thursday declared Florida's ban on same-sex marriage unconstitutional, joining state judges in four counties who have sided with gay couples.

U.S. District Judge Robert L. Hinkle ruled that the ban added to Florida's constitution by voters in 2008 violates the 14th Amendment's guarantees of equal protection and due process. Hinkle issued a stay delaying the effect of his order, meaning no marriage licenses will be immediately issued for gay couples.

Hinkle, an appointee of President Bill Clinton, compared bans on gay marriage to the long-abandoned prohibitions on interracial marriage and predicted both would be viewed by history the same way.

"When observers look back 50 years from now, the arguments supporting Florida's ban on same-sex marriage, though just as sincerely held, will again seem an obvious pretext for discrimination," Hinkle wrote. "To paraphrase a civil rights leader from the age when interracial marriage was struck down, the arc of history is long, but it bends toward justice."

Florida Attorney General Pam Bondi has appealed the previous rulings striking down the ban in Broward, Miami-Dade, Monroe and Palm Beach counties. Hinkle's ruling allows time for appeals in the federal case. Bondi has said the Florida cases should await a final ruling on gay marriage by the U.S. Supreme Court.

A number of similar rulings around the country have been put on hold while appeals are pursued.

The latest Florida ruling came in a pair of lawsuits that brought by gay couples seeking to marry in Florida and others who want to force Florida to recognize gay marriages performed legally in other states.

Currently, 19 states and the District of Columbia permit same-sex marriage.

Gay marriage proponents have won more than 20 legal decisions against state same-sex marriage restrictions since the U.S. Supreme Court invalidated the federal Defence of Marriage Act last year.

On Wednesday, the Supreme Court delayed an appeals court decision that would end Virginia's gay marriage ban and, in January, the justices did the same thing in a same-sex marriage case in Utah. The 6th U.S. Circuit Court of Appeals recently heard arguments in six same-sex marriage cases from Michigan, Ohio, Kentucky and Tennessee.

The American Civil Liberties Union of Florida, which represented some of the gay couples, said the tide of rulings makes legal same-sex marriage in Florida appear inevitable.

"We're very pleased to see the ban held unconstitutional in such unequivocal terms so that all Florida families will soon finally have the same protections," said ACLU staff attorney Daniel Tilley.