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California went on the offensive Tuesday against the Trump administration’s plan to weaken fuel-efficiency rules for cars, laying out a scathing rebuttal that the state’s clean-air regulator said would shape the battle with Washington in the coming months and years.

The state’s target is one of President Trump’s most consequential environmental rollbacks to date, a proposal unveiled last week to let cars pollute more while stripping California of its right to set its own air-quality rules.

The administration’s proposal “is contrary to the facts and the law,” the California document says, before refuting point by point the Trump administration’s arguments for weakening the nation’s long-term goals for making vehicles more fuel efficient and less polluting.

The clash between California and Washington threatens to throw the United States auto market into disarray. Because California has the authority under the Clean Air Act to set its own air pollution rules, and because a dozen other states follow its lead, the dispute could effectively split the nation’s market into two, one side adhering to stringent emissions rules set in Sacramento and the other to weaker federal standards.