WASHINGTON (Reuters) - Republicans and Democrats in Congress sparred on Tuesday over U.S. states setting rules for testing and deployment of self-driving cars and a proposal to allow automakers and technology companies to bypass existing regulations in introducing autonomous cars.

A prototype of Google's own self-driving vehicle is seen during a media preview of Google's current autonomous vehicles in Mountain View, California September 29, 2015. REUTERS/Elijah Nouvelage

Democrats on a U.S. House Energy and Commerce subcommittee said that the U.S. National Highway Traffic Safety Administration (NHTSA) must play a more aggressive role in mandating self-driving car safety.

A Republican draft package of 14 bills would allow NHTSA to exempt up to 100,000 vehicles per year from federal motor vehicle safety rules, which currently prevent the sale of self-driving vehicles without human controls. It would also bar states from setting self-driving rules and prevent NHTSA from preapproving self-driving car technologies.

“We simply cannot have cars that stop at state lines,” Representative Robert Latta said at a hearing of the subcommittee. “This isn’t the government saying you have to get in a self-driving car. This is government make sure that industry can innovate.”

Latta said he hoped to win committee approval of a bipartisan legislative package by the end of July.

General Motors Co, Alphabet Inc, Tesla Inc and others have been lobbying Congress to pre-empt rules under consideration in California and other states that could limit self-driving vehicle deployment.

Representative Frank Pallone, a Democrat, said that under the Republican proposal, states would be barred from regulating self-driving car safety “without a guarantee that NHTSA will step in” to set binding rules. “We need to be sure that we get this right and that safety is the first priority,” Pallone said.

Democrats noted that the administration of President Donald Trump, a Republican, has not nominated a candidate to head NHTSA, which has a number of vacant senior positions. NHTSA did not sent an official to testify.

Two automaker trade associations said in testimony it is essential they do not face a “patchwork” of self-driving state rules. They said NHTSA will have to approve exemptions.

Republicans, citing competition from other countries and the rising number of traffic deaths, say it is urgent Congress approve sweeping legislation to ensure automakers and technology companies test the vehicles inside the United States.

The administration of former Democratic President Barack Obama last year unveiled voluntary guidelines on self-driving cars. Trump’s Transportation Secretary Elaine Chao has vowed to quickly update those.