(CNN) The Trump administration has cut off talks with California over vehicle emission standards, setting up another high-profile legal showdown between the Democratic-controlled state and the Trump administration.

This time, the dispute is over California's authority to set its own auto emission standards that are stricter than the Trump administration's proposal. The Trump administration is expected to slow down or freeze annual increases the Obama administration scheduled each year until 2025.

Automakers cringe at the concept of two different auto markets in the US resulting from two different standards: one, set by California that also applies to 13 other states that follow its lead, and the federal standard that applies elsewhere.

California and the 13 states that follow it make up 40% of the US auto market, according to Dan Becker, whose Safe Climate Campaign backs California's position.

California regulators want to retain their decades-old authority to set pollution standards that stems from the 1970 Clean Air Act, and their environmentalist allies fear a weak or non-existent standard set by the Trump administration.

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