The letter, signed by Democrats Gary Peters, Ron Wyden, Dick Durbin, Patty Murray went to Tesla CEO Elon Musk and top executives at Toyota Motor, Volkswagen, Hyundai, Rivian, Mercedes-Benz, Honda and others and urged them to pledge not to interfere in any organizing activities.

"We believe a neutrality agreement is the bare minimum standard manufacturers should meet in respecting workers' rights, especially as companies receive and benefit from federal funds related to the electric vehicle transition," the letter seen by Reuters said.

(Reporting by David Shepardson; Editing by Chizu Nomiyama)