House Republicans are ramping up the pressure on the Senate, particularly its Democratic members, to advance legislation on self-driving vehicles before Congress adjourns for the 2018 midterm elections.

The House unanimously passed a bill to create an initial regulatory framework for autonomous driving technology earlier this year, but the Senate's measure has halted amid opposition from several members. House GOP leaders blame Senate Democrats for objecting to the bill on behalf of trial attorneys concerned that the bill would allow companies to force customers into private arbitration.

"Trial lawyers are in somebody's pocket somewhere, and it's going to cost lives in America. It's going to cost jobs in America," House Energy and Commerce Chairman Greg Walden of Oregon told reporters. "Unless you want innovation in this space to go to China, Singapore, and Germany, you should act."

[Related: Race to develop self-driving cars unabated by string of fatal crashes]

Among those blocking the measure is Democratic Sen. Dianne Feinstein of California, the headquarters for many U.S. businesses working on autonomous technology. She and four other Democratic senators expressed concerns about the bill in a letter to Senate Commerce Committee Chairman John Thune of South Dakota and Sen. Gary Peters, D-Mich., earlier this year.

"Until new safety standards are put in place, the interim framework must provide the same level of safety as current standards," the lawmakers wrote. "Self-driving cars should be no more likely to crash than cars currently do, and should provide no less protection to occupants or pedestrians in the event of a crash."

A Feinstein spokesperson didn't immediately respond to a request for a comment.

Despite the lack of a federal framework governing the technology, investment dollars have flowed into it, and U.S. automakers have formed several partnerships with developers.

Toyota, for example, recently invested $500 million in Uber and teamed with the ride-hailing company on its self-driving program. General Motors invested $500 million in Lyft's autonomous vehicle initiative, then bought self-driving technology firm Cruise Automation, and Fiat Chrysler partnered with Waymo, owned by Google's parent company, Alphabet Inc.

Walden argued that companies and investors would be more willing to invest money and resources if there were certainty over how self-driving vehicles would be regulated.

"What you never see is what you didn't get," he said.

Several states have advanced their own bills on the issue, leading to concerns that a patchwork approach to regulation could limit advancement.

"We can't have 50 states and the District of Columbia out there with their own legislation," said Rep. Bob Latta, an Ohio Republican and lead sponsor of the bill. "We don't want these cars being developed or people out there not knowing exactly what they should have, and cars shutting off when they get to state lines."

Proponents of self-driving car technology say it could dramatically reduce the number of deaths on U.S. roads each year, but the vehicles carry risks of their own.

A 49-year old woman was killed in Tempe, Ariz., in March after she was struck by one of Uber's autonomous cars, whose human backup driver was watching video on a mobile phone at the time, according to police.

The same month, a 38-year-old Apple engineer died when his Tesla Model X caught fire after striking a barrier in Mountain View, Calif., and being hit by two other cars.

The automaker subsequently said that the car's Autopilot technology had been activated before the collision, with its adaptive cruise control follow-distance set to minimum, and that the system gave several audible and visual warnings before impact.