Federal education officials said on Friday that they had opened a civil rights inquiry into whether New York State could withhold state money from a Long Island school district that has refused to follow a state requirement and drop its Native American mascot.

The announcement came shortly after President Trump expressed his support for the district, in Massapequa, N.Y., in its fight against complying with a state Board of Regents requirement that all districts abandon mascots that appropriate Native American culture or risk losing state funding.

The Massapequa district, whose “Chiefs” logo depicts an illustrated side profile of a Native American man in a feathered headdress, is one of several that have resisted making a change.

The name of the town, a middle-class swath of the South Shore where most residents voted for Mr. Trump in the November election, was derived from the Native American word “Marspeag” or “Mashpeag,” which means “great water land.”

In announcing the investigation, Linda McMahon, the education secretary, said that her department would “not stand by as the state of New York attempts to rewrite history and deny the town of Massapequa the right to celebrate its heritage in its schools.”

JP O’Hare, a spokesman for the state Education Department, said in a statement that state education officials had not been contacted by the federal government about the matter.

“However,” he added, “the U.S. Department of Education’s attempt to interfere with a state law concerning school district mascots is inconsistent with Secretary McMahon’s March 20, 2025, statement that she is ‘sending education back to the states, where it so rightly belongs.’”

The policy, introduced in 2022, was adopted amid a national push to change Native American mascot names or iconography through legislation and other moves.

When the ban was adopted, about five dozen New York school districts still used Native American-inspired mascots and logos. Districts were given until the end of June this year to eliminate banned mascots.

Since taking office for his second term, Mr. Trump and his administration have waged a relentless campaign against what they argue are illegal diversity, equity and inclusion initiatives and have threatened entities that do not fall in line and eliminate such efforts.

The president has said he would slash funding for low-income students in states that fail to do away with such programs. New York’s Education Department was the first to publicly refuse to comply with the order.

Massapequa school leaders filed a federal lawsuit seeking to keep the “Chiefs” name, but the judge in the case recently moved closer to dismissing it after finding they had failed to provide sufficient evidence for their claims, including that the mascot qualified as protected speech.

In a social media post this week, Mr. Trump criticized New York’s policy and called for Ms. McMahon to intervene.

“Forcing them to change the name, after all of these years, is ridiculous and, in actuality, an affront to our great Indian population,” the president wrote.

In a statement included in the federal Education Department’s announcement, Kerry Watcher, the Massapequa Board of Education president, welcomed the investigation.

“Attempts to erase Native American imagery do not advance learning,” Ms. Watcher said. “They distract from our core mission of providing a high-quality education grounded in respect, history and community values.”

A coalition of 19 states sued the Trump administration on Friday over its threat to withhold federal funding from states and districts with certain diversity programs in their public schools.

The lawsuit was filed in federal court by the attorneys general in California, New York, Illinois, Minnesota and other Democratic-leaning states, who argue that the Trump administration’s demand is illegal.

The lawsuit centers on an April 3 memo the Trump administration sent to states, requiring them to certify that they do not use certain diversity, equity and inclusion programs that the administration has said are illegal.

States that did not certify risked losing federal funding for low-income students.

Rob Bonta, the California attorney general, said at a news conference on Friday that the Trump administration had distorted federal civil rights law to force states to abandon legal diversity programs.

“California hasn’t and won’t capitulate. Our sister states won’t capitulate,” Mr. Bonta said, adding that the Trump administration’s D.E.I. order was vague and impractical to enforce, and that D.E.I. programs are “entirely legal” under civil rights law.

The Trump administration did not immediately respond to a request for comment on Friday evening.

The administration has argued that certain diversity programs in schools violate federal civil rights law, which prohibits discrimination on the basis of race, color and national origin in programs that receive federal funding.

It has based its argument on the Supreme Court’s 2023 ruling ending the use of race in college admissions, arguing that the decision applies to the use of race in education more broadly.

The administration has not offered a specific list of D.E.I. initiatives it deems illegal. But it has suggested that efforts to provide targeted academic support or counseling to specific groups of students amount to illegal segregation. And it has argued that lessons on concepts such as white privilege or structural racism, which posits that racism is embedded in social institutions, are discriminatory.

The lawsuit came a day after the Trump administration was ordered to pause any enforcement of its April 3 memo, in separate federal lawsuits brought by teachers’ unions and the N.A.A.C.P., among others.

Mr. Bonta said that the lawsuit by the 19 states brought forward separate claims and represented the “strong and unique interest” of states to ensure that billions of federal dollars appropriated by Congress reach students.

“We have different claims that we think are very strong claims,” he said.

Loss of federal funding would be catastrophic for students, said Letitia James, the attorney general of New York, an adversary of President Trump who previously won a civil fraud case against him.

She noted that school districts in Buffalo and Rochester rely on federal funds for nearly 20 percent of their revenue and said she was suing to “uphold our nation’s civil rights laws and protect our schools and the students who rely on them.”