The leaders of the world’s biggest car companies are heading to the White House on Friday, and it may be their last chance to prevent a head-on collision between the Trump administration and the state of California.

The administration wants to cut back dramatically on Obama-era emissions regulations, which are supported by California and other states. The president and his senior advisers have indicated they are ready to confront local resistance to the rules rollback, but they also have shown frustration over what they describe as tepid support from car makers for the regulatory initiative.

The White House, along with environmental and transportation regulators, are bringing in chief executives from General Motors Co. , Ford Motor Co. and Fiat Chrysler Automobiles NV, as well as other car company representatives, to forge a common stance over fuel-economy requirements.

Auto makers have complained the current standards for their cars and trucks are too rigorous, saying they don’t reflect consumer demand. But the rollback being pushed by the White House is so extensive, some are concerned it will cause more problems than it seeks to solve.

High on the agenda will be California, which has its own powers over fuel-efficiency standards and is already suing to stop the administration’s overhaul. That has escalated a power struggle between Washington and Sacramento that some fear could result in auto makers having to meet two different standards for selling cars and trucks in the U.S.