General Motors, Ford , Stellantis and Toyota Motor North America on Monday urged Congress to lift a cap on the US$7,500 electric vehicle tax credit, citing higher costs to produce zero-emission vehicles, according to a letter seen by the Reuters news agency.

Automaker CEOs – GM’s Mary Barra, Ford’s Jim Farley, Stellantis’ Carlos Tavares and Toyota North America CEO Tetsuo Ogawa – said in the joint letter to congressional leaders they had pledged to invest over $170 billion through 2030 to bolster electric vehicles’ development, production and sale.

The current $7,500 tax credit phases out after a manufacturer hits 200,000 vehicles sold. Both GM and Tesla have already hit the cap and are no longer eligible for the consumer tax credits.

“We ask that the per-(automaker) cap be removed, with a sunset date set for a time when the EV market is more mature,” the automakers said in the letter, according to Reuters.

“Recent economic pressures and supply chain constraints are increasing the cost of manufacturing electrified vehicles which, in turn, puts pressure on the price to consumers.”

Reuters noted the letter came amid growing concerns among auto industry executives that the window was closing for US congress to extend electric vehicle tax credits given Republicans may retake control of one or both houses of congress next year.

Last week, Ford executive chairman Bill Ford made an unannounced trip to Capitol Hill to make the case for extending the tax credit, the report said.

In April, Reuters noted, senator Joe Manchin, a key Democrat, questioned the need to extend electric vehicle tax credits in the face of strong consumer demand and Chinese production of battery components.

“There’s a waiting list for EVs right now with the fuel price at $4. But they still want us to throw $5,000 or $7,000 or $12,000 credit to buy electric vehicles. It makes no sense to me whatsoever,” Manchin said. “When we can’t produce enough product for the people that want it and we’re still going to pay them to take it – it’s absolutely ludicrous in my mind.”

Reuters noted Toyota said in April it expected its credits would expire by the end of 2022 after it hits the cap.

Ford sold nearly 160,000 electric vehicles through the end of 2021 and could hit the cap this year.