From the Overview: "On December 10, 2019, the United States, Canada, and Mexico agreed to a protocol of amendment to the proposed U.S.-Mexico-Canada Agreement (USMCA). The amendments include modifications to key elements of the original text in regard to dispute settlement, labor and environmental provisions, intellectual property rights (IPR), and steel and aluminum requirements in the rules of origin for autos. On December 13, the Trump Administration submitted to Congress the proposed USMCA implementing legislation, which also reflects the recent amendments. [...] The U.S. Trade Representative (USTR) and some Members of Congress negotiated proposed changes to the USMCA to address ongoing congressional concerns. USTR then negotiated the amendments with USMCA parties. Mexico was the first country to ratify the agreement in June 2019 and approve the amendments by a 107-1 vote in the Mexican Senate on December 12, 2019. Canada's Parliament is expected to ratify it in early 2020. Congress is considering USMCA under TPA rules, which is the time-limited authority that Congress uses to consider implementing legislation for trade agreements under expedited procedures, provided that they meet certain statutory requirements. Under TPA [Trade Promotion Authority], Congress has a maximum of 90 legislative days to vote on the agreement."
CRS In Focus, IF11391
Congressional Research Service: https://crsreports.congress.gov/