The U.S. Senate Commerce Committee plans a hearing next Wednesday on the future of self-driving commercial trucks that will include the chief executive of Navistar International Corp. and safety advocates.

A U.S. House bill aimed at speeding self-driving vehicles to market that faces a vote Wednesday does not include changes to allow fully autonomous commercial trucks on U.S. roads, but some senators want to include commercial trucks.

The Teamsters union has praised efforts to keep self-driving commercial trucks out of a proposed bill aimed at speeding deployment of the advanced technology for cars, warning that truck driver jobs may be at risk.

"Self-driving technology for trucks and other large vehicles has emerged as a pivotal issue in Congress’ attempt to help usher in a new era of transportation," said Senator John Thune, who chairs the Commerce Committee.

Also testifying will be Deborah Hersman, president of the National Safety Council, as well as the head of the American Trucking Associations and chief of the Colorado State Patrol.

Alphabet Inc’s self-driving car unit Waymo is working on developing self-driving trucks, the company said in June.

Other companies have also been working on self-driving trucks. Ride services company Uber Technologies is working on autonomous trucking through its Otto unit, acquired last year. Tesla Inc, which is working on self-driving technologies, said in April it plans to unveil a commercial truck called the Tesla Semi this month.

U.S. Transportation Secretary Elaine Chao has said she is “very concerned” about the impact of self-driving cars on U.S. jobs, a big part of President Donald Trump’s campaign message.

The Teamsters, which represent 1.4 million workers including hundreds of thousands of truck drivers, have lobbied to keep commercial trucks out of the self-driving legislation.

Auto industry leaders have said 3 million commercial truck jobs could eventually be at risk if self-driving vehicles replaced human drivers.

The Teamsters have opposed efforts by states to approve plans by logistics companies to use platooning technology that could reduce driver jobs by allowing a pack of trucks to be digitally connected and driven in formation.