Denver this week sued the Trump administration over its threat to withhold as much as $600 million in federal transportation funding if the city refuses to align its politics with the president’s stances on issues of immigration and diversity.

Denver joined nearly three dozen other cities and counties in the 105-page lawsuit, filed Wednesday in U.S. District Court for the Western District of Washington.

The cities and counties take issue with U.S. Transportation Secretary Sean Duffy’s April memo that warned local jurisdictions they could lose access to federal transportation funding if they do not comply with the Trump administration’s positions on both immigration enforcement and diversity, equity and inclusion efforts.

Any program or policy “designed to achieve so-called ‘diversity, equity and inclusion,’ or ‘DEI,’ goals, presumptively violates federal law,” Duffy warned in the memo. Localities receiving federal funds must also fully cooperate with federal immigration enforcement or risk losing the money, he wrote.

The cities and counties that sued argue the new federal conditions on awarding the funding are unconstitutional and that the Trump administration does not have the authority to set conditions beyond what Congress has established.

“The Trump administration is willfully breaking the law and, in ignoring the separation of powers between Congress and the White House, violating the bedrock constitutional foundation on which our country was built,” Denver Mayor Mike Johnston said in a statement Friday.

Denver’s Department of Transportation and Infrastructure is the recipient of about $300 million in federal funding, while Denver International Airport received about $310 million between the 2022 and 2024 fiscal years, according to the mayor’s office.

The airport is expected to be eligible for an additional $267 million in grants from 2025 to 2028, a city spokesman said in a news release.

Across the almost three dozen cities and counties that are suing — including San Francisco, New York, Boston, Seattle, Minneapolis, Pittsburgh and Nashville, Tennessee — almost $4 billion in awarded or soon-to-be awarded federal funding is at risk, the lawsuit alleges.

“Allowing the unlawful grant conditions to stand would negatively impact Plaintiffs’ committed budgets, force reductions in their workforce, and undermine their ability to determine for themselves how to meet their communities’ unique needs,” the lawsuit says.

The effort is Denver’s second lawsuit this month against the Trump administration. The city last week joined a lawsuit with Chicago after the Federal Emergency Management Agency refused to pay Denver $24 million in previously awarded grant money.

Additionally, the U.S. Department of Justice sued Denver and Colorado earlier in May over state and local laws that limit how much local police can cooperate with federal immigration officials.

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Originally Published: May 23, 2025 at 1:14 PM MDT