California air-pollution regulators want to meet with Trump administration officials over plans to ease federal auto-efficiency standards, saying in a letter to the White House that efforts to undermine the state’s authority would run afoul of the law.

Over and over in their decadeslong war on smog, Southern California regulators have failed to use a powerful tool against ports, warehouses and other freight and logistics hubs that are magnets for air pollution.

The Trump administration will argue that the high cost of meeting Obama-era fuel economy standards discourages motorists from trading in less-efficient vehicles, as it sets about weakening the rules, said people familiar with the discussions.

California and the Trump administration are on a collision course over auto-efficiency regulations that could lead the White House to deploy the nuclear option: revoking the state’s cherished power to set its own limits on air pollution.