The agreement was initially pursued by conservative governments in the United States and Canada supportive of free trade, led by Canadian Prime Minister Brian Mulroney, U.S. President George H. W. Bush, and the Mexican President Carlos Salinas de Gortari. The three-nation NAFTA was signed on 17 December 1992, pending its ratification by the legislatures of the three countries. There was considerable opposition in all three countries, but in the United States it was able to secure passage after Bill Clinton made its passage a major legislative initiative in 1993. During his presidential campaign he had promised to review the agreement, which he considered inadequate. Since the agreement had been signed by Bush under his fast-track prerogative, Clinton did not alter the original agreement, but complemented it with the aforementioned NAAEC and NAALC. After intense political debate and the negotiation of these side agreements, the U.S. House passed NAFTA by 234-200 (132 Republicans and 102 Democrats voting in favor, 156 Democrats, 43 Republicans, and 1 independent against).
and the U.S. Senate passed it by 61-38
Finally, Clinton sanctioned the ratification in November 1993.