In another embarrassment to President Bush, the Senate voted 70-30 yesterday to end a Republican filibuster and support efforts to impose stricter safety standards on Mexican trucks driving across the United States. Granting Mexican trucking companies access to American roads has been a contentious issue since the 1993 North American Free Trade Agreement. President Bush has stated that he wants to allow Mexican trucks in the US beginning January 1. At first the administration proposed allowing the trucks to enter and then auditing the Mexican companies over the next eighteen months. After this plan was criticized, the White House agreed to hold periodic inspections on the border. The issue pits highway safety advocates and labor unions, especially the Teamsters, on one side, and businesses and trucking companies on the other. While the House version of the transportation spending bill included a complete ban on Mexican trucks outside of a 20-mile commercial zone along the border, the Senate version includes regular inspections of Mexican trucks and drivers, on-site audits of Mexican trucking companies, and more inspectors and scales at border stations. Supporters of these standards claim that lenient safety rules in Mexico will result in large numbers of unsafe trucks on American highways. Opponents characterize the measure as "anti-Mexican" (the same rules will not apply to Canadian trucks) and warn that it will violate NAFTA. President Bush has threatened to stop the new plan, even if it means vetoing the entire Senate transportation bill.