Those deficiencies suggest that even with unified Republican control of Congress, Trump will struggle to post many, and perhaps any, landmark legislative victories. But far from the headlines, in decisions usually announced in the small print of the Federal Register, his administration is making a sharp turn to the right in virtually every federal department and agency. Cumulatively, these executive actions amount to an organized assault on Democratic priorities and a hard tilt toward corporate and conservative preferences.

“If there is something [already] on the books, the administration has enormous ability to establish its enforcement priorities,” said Douglas Holtz-Eakin, the president of the American Action Forum, a center-right think tank. “They can switch an awful lot very quickly, and they have.”

The lawsuit filed Monday captures the trench warfare that is now unfolding far from the daily dumpster fire of White House controversies. The suit is rooted in legislation Congress approved in 2012 that, for the first time, required states to establish quantitative benchmarks to measure whether federal transportation dollars were helping them achieve seven specific goals. Those included promoting safety, reducing congestion, and encouraging environmental sustainability. Toward that last objective, the Obama administration issued regulations just before it left office requiring states to track and report greenhouse-gas emissions on their highways, and to set goals for reducing them.

Deron Lovaas, an urban-issue specialist at the NRDC, explained that those regulations were intended to complement rules the Obama administration had issued requiring automakers to improve the fuel efficiency of cars and trucks. “This addresses traffic,” he told me. “Over the long run, no matter how good and clean vehicles become … your gains [in reducing emissions] can be outstripped if traffic continues to increase unchecked.”

With transportation now exceeding electricity generation as the largest source of U.S. greenhouse-gas emissions, environmental groups believe the highway rule could prompt creative thinking from local governments about how to reduce traffic—from promoting mass transit to reconsidering land-use patterns. A similar California state requirement has shown promise on exactly those fronts.

But after taking office, the Trump administration twice delayed the reporting requirement for highway emissions. Then in May, it shelved the rule indefinitely, while allowing other reporting and target requirements to proceed. The environmentalists’ lawsuit, now in federal district court in New York, claims these decisions violated federal administrative procedure because they were taken without any opportunity for public input. (The highway administration said it does not comment on pending lawsuits.)