When the framers signed the Constitution on September 17, 1787, they still faced the arduous task of persuading the American people to agree with them. And the framers did not even agree among themselves. Only thirty-nine of the fifty-five delegates who attended the Constitutional Convention signed the final version of the Constitution. The nation quickly divided into two factions: the Federalists, who supported ratification of the Constitution, and the Antifederalists, who opposed it. Eventually the Federalists prevailed, once they had promised Americans that a bill of rights would be added to the Constitution as soon as the new Congress convened.