The CEOs of several automakers signed a letter addressed to the United States Congress asking for the removal of the 200,000 unit cap on electrified vehicle incentive eligibility.

The CEOs, among them GM’s Mary Barra, Ford’s Jim Farley, Stellantis’ Carlos Tavares, and Toyota’s North American CEO Tetsuo Ogawa, asked that a sunset date for ending tax incentives for electric and plug-in hybrid vehicles be introduced instead of a strict number, reports Reuters. Currently, Tesla and GM have both sold more than 200,000 electrified vehicles each and no longer qualify for federal incentives worth up to $7,500.

In their letter, the CEOs argued that their companies have together pledged to invest over $170 billion through 2030 to bolster the development of EVs. They also cited anxiety about the high prices of manufacturing EVs and recent issues with the supply of semiconductor chips and other parts.

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“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. “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.”

The letter was signed as the prospect of midterm elections loom. The automakers may be attempting to get Congress to implement these changes before Democrat control is challenged.

Support among Democrats may not be as strong as one might assume, though. In April, Senator Joe Manchin, a major figure in the Democratic party, questioned the need to extend electric vehicle tax credits.

“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,” he 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.”

President Joe Biden, though, has been interested in using incentives to support the adoption of EVs. His administration proposed expanding the credit to $12,500 on American union-made EVs. This letter did not, however, address that proposal, which was opposed by Toyota.