Under the new agreement, 75% of North American cars must be produced in the region, and 40 percent of cars must be manufactured in factories that pay workers at least $16 an hour. The agreement is also expected to increase U.S. agricultural exports by $2 billion, with a total GDP increase of $65 billion. Growing objections within Member States to U.S. trade policy and various aspects of the USMCA have had an impact on the signing and ratification process. Mexico said it would not sign the USMCA if tariffs on steel and aluminum were maintained.  Based on the results of the November 6, 2018 U.S. election, it has been speculated that the greater power of Democrats in the House of Representatives could jeopardize the passage of the USMCA agreement.   Bill Pascrell, a senior Democrat, argued for changes to the USMCA to pass Congress.
 Republicans have opposed the USMCA provisions that impose labour rights on LGBTQ and pregnant workers.  Forty Republicans in Congress have asked Mr. Trump not to sign an agreement that includes “the unprecedented integration of sexual orientation and the language of gender identity.” As a result, Trump ultimately signed a revised version that required each nation only to “policies it deems appropriate to protect workers from discrimination in the workplace” and said the United States would not be required to introduce additional non-discrimination laws.  The Canadian government expressed concern about the changes that have occurred under the USMCA agreement.  Under NAFTA, the parties challenging the trade agreement were able to challenge it through an international resolution body. On December 19, 2019, the U.S. House of Representatives passed the USMCA with multiparty support with 385 votes (Democracy 193, Republican 192) to 41 (Democracy 38, Republican 2, Independent 1).  On January 16, 2020, the U.S.
Senate passed the trade agreement by 89 votes (Democrats 38, Republicans 51) to 10 (Democracy 8, Republican 1, Independent 1) and the bill was forwarded to the White House for the signature of Donald Trump.  On January 29, 2020, Trump signed the agreement (Public Law No: 116-113).  NAFTA has been formally amended, but not the 1989 Canada-U.S. Free Trade Agreement, which is only “suspended.”   Negotiations focused “primarily on car exports, steel and aluminum tariffs, as well as the milk, egg and poultry markets.” A provision “prevents any party from enacting laws that restrict the cross-border flow of data.”  Compared to NAFTA, the USMCA increases environmental and labour standards and encourages domestic production of cars and trucks.  The agreement also provides up-to-date intellectual property protection, gives the U.S. more access to the Canadian milk market, imposes a quota for Canadian and Mexican auto production, and increases the customs limit for Canadians who purchase U.S. products online from $20 to $150.  The full list of differences between USMCA and ALEFTA is listed on the Website of the United States Trade Representative (USTR).  On November 30, 2018, the USMCA was signed as planned by the three parties at the G20 summit in Buenos Aires.   Disputes over labour rights, steel and aluminum prevented ratification of this version of the agreement.
  Canadian Deputy Prime Minister Chrystia Freeland, U.S. Trade Representative Robert Lightizer, and Mexican Under-Secretary of State for North America Jesus Seade officially signed a revised agreement on December 10, 2019, ratified by the three countries on March 13, 2020.