Several lawmakers expressed skepticism during a congressional hearing on Wednesday about the Bush administration's plan to allow Mexican trucks access to all U.S. roads by the end of the year.

Transportation Secretary Norman Mineta, testifying before the Senate Commerce, Science and Transportation Committee, assured lawmakers that Mexican trucks will be required to follow the same regulations as U.S. trucks. After two hours of testimony, Mineta failed to convince skeptical lawmakers.

"I think this is a very ambitious program to get this done by the end of the year," said Sen. George Allen (R-VA). Allen told Mineta that to get support for the administration plan, the agency would need to "perform more duties than you think are necessary."

Sen. Barber Boxer (D-CA) also expressed concern for the administration's plan. "This is a nightmare and we are not ready for this," Boxer said.

Kenneth Mead, transportation department inspector general, said after the hearing that he also considers the administration plan ambitious.

The administration has pledged to add more inspectors to perform Level 1 inspections at border crossings and tougher inspection procedures at all 27 border crossings. The Senate is scheduled to debate cross-border trucking within the next few days when it considers the transportation spending bill.