WASHINGTON >> Lawmakers in the House took a major step today toward advancing the development of driverless cars, approving legislation that would put the vehicles onto public roads more quickly and curb states from slowing their spread.

Under the bill, which was approved by a unanimous voice vote, carmakers can add hundreds of thousands of self-driving cars to U.S. roads in the next few years. States, which now have a patchwork of rules regulating the vehicles, would have to follow the new federal law.

The House vote sets the stage for a battle between safety advocates and companies that make driverless vehicles. Automakers say the vehicles could greatly reduce roadway fatalities and help their businesses, but many safety advocates say they are not ready for wide deployment. The next steps will come in the Senate, which is expected to consider a similar bill soon.

Lawmakers who support the legislation said the country’s confusing regulatory environment was hampering the driverless-car industry’s prospects.

“Self-driving cars have the potential to save lives, especially when the majority of fatalities are caused by human error,” said Rep. Debbie Dingell, D-Mich. “The question is whether we are in the driver’s seat and not to cede it to China or India.”

Auto and technology giants, including Ford Motor, General Motors and Waymo, Alphabet’s driverless division, have pushed hard for the new law. They have also pressed regulators at the National Highway Traffic Safety Administration to clarify safety guidelines covering self-driving technology. Elaine L. Chao, the transportation secretary, is expected to announce revised guidelines for the vehicles next week in Michigan.

In recent years, dozens of states have passed laws related to self-driving safety, some of which carmakers view as too heavy-handed. The companies have, for example, fought proposals in California, Michigan and New York that would require driverless cars to be electric-powered and to contain steering wheels and brake pedals.

“The reason why Congress is doing this is that there was a growing concern of a vacuum created because NHTSA hadn’t acted and the states were acting in NHTSA’s place,” said Marc Scribner, a senior fellow at the Competitive Enterprise Institute, a conservative-leaning research group in Washington.