President Trump and the leaders of Canada and Mexico announced the most significant trade deal in a generation a year ago this week. The U.S.-Mexico-Canada Agreement is unambiguously a win for America. It would create new jobs, expand export markets, strengthen protections for workers, and generate billions of dollars in new prosperity. The USMCA would also help keep North American partners close while the U.S. hangs tough with China.

Mexico has ratified the agreement. Canada is waiting for us to take the lead. The U.S. Senate...