Bill Nelson, Fla. Sen., declares support for gay marriage

U.S. Sen. Bill Nelson has joined the growing number of senators to endorse gay marriage.

The Florida Democrat wrote Thursday in a Tampa Bay Times column, "The civil rights and responsibilities for one must pertain to all. Thus, to discriminate against one class and not another is wrong for me."

Nelson pledged to add his name to the petition of senators asking the U.S. Supreme Court to declare the law that prohibits gay marriage unconstitutional.

The moderate Nelson had previously supported civil unions for gay people but said he believed marriage should be between a man and a woman.

With Nelson's shift, only six Senate Democrats remain opposed to gay marriage. A handful of Republicans, including Ohio Sen. Rob Portman, have also changed their stance