The Democratic-controlled U.S. House of Representatives threw its weight behind an ambitious lawsuit Friday that targets the Trump administration’s “sabotage” of the Affordable Care Act, asserting that anti-ACA actions have harmed millions of Americans.

In an amicus brief filed in Maryland federal court, the House championed a sprawling lawsuit filed by several major cities, agreeing with their argument that the administration has intentionally damaged the ACA with a series of subversive regulatory moves.

“The administration has undermined the Affordable Care Act, and it has harmed the millions of Americans who depend on the act to access quality, affordable health insurance,” the House wrote.

Much of the House’s brief focused on a rule that the Centers for Medicare & Medicaid Services issued last year to govern the ACA’s insurance marketplaces. The lawsuit — filed by the cities of Philadelphia, Baltimore, Chicago, Cincinnati and Columbus, Ohio — seeks to undo many elements of that rule.

The House on Friday singled out the rule’s elimination of certain “standardized options” for health insurance, contending that the change inhibits comparison shopping. It also criticized the rule’s elimination of a requirement that consumer-assistance “navigators” live in the area they serve, saying that the change undermines the navigators’ effectiveness.

The House also rapped the administration for shortening the ACA’s open enrollment period, cutting spending on consumer outreach and failing to set enrollment targets, averring that the steps were “designed to reduce enrollment.”

Additional amicus briefs on Friday came from a coalition of cities and counties, a Brookings Institution scholar and various nonprofit groups, including the pro-ACA group Families USA.

The administration has sharply criticized the lawsuit, arguing that its policies have stayed well within the bounds of permissible executive branch action and that the cities haven’t described any concrete harms, so they have no legal standing.

Notably, after the administration filed a motion to dismiss in December, the cities filed an amended complaint without waiting for a ruling on the motion. The administration in March filed a new motion to dismiss, which is pending.

Enrollment in private ACA plans peaked at 12.7 million in 2016 and has since dropped steadily, dropping to 11.4 million in 2019. Virtually the entire decline has occurred in federal ACA marketplaces overseen by the executive branch, whereas enrollment via state ACA marketplaces has been essentially flat.

A representative of the U.S. Department of Justice, which is defending the suit, could not immediately be reached for comment Friday.

The plaintiff cities are represented by the Columbus City Attorney’s Office, the City of Baltimore Department of Law, the Office of the City Solicitor of Cincinnati, the City of Chicago Department of Law, the City of Philadelphia Law Department, and the Democracy Forward Foundation.

The House is represented by its Office of General Counsel and by the Constitutional Accountability Center.

The administration is represented by the U.S. Department of Justice’s Civil Division.

The case is City of Columbus et al. v. Trump et al., case number 1:18-cv-02364, in the U.S. District Court for the District of Maryland.