Supporters of Amendment 6 have said their final goal is a law that requires parental consent for young women's abortions, now impossible because of a 1989 Florida Supreme Court ruling the new initiative would void.
The group Say Yes on 6 said parental consent is a sensible policy necessary to ensure the well-being of young women.
"Parents are responsible for the health and well-being of their children, and their consent is required for body piercing, medication at school and other medical procedures. We believe that abortion should not be exempt from parental consent," the group states on its website.
The Center for Reproductive Rights praised the amendment's defeat Tuesday.
"We commend the voters of Florida for joining what has become a national movement to wholly reject these attacks on reproductive freedom and to demand stronger protections for reproductive rights," said Nancy Northup, president and CEO at the Center for Reproductive Rights, in a statement.