As the White House targets diversity, equity and inclusion efforts in public schools, President Trump is stepping into a local issue that rarely attracts the attention of leaders in Washington by taking on a school mascot.

Mr. Trump this week homed in on a suburban hamlet on Long Island, where the public school district is ensnared in a lengthy, bitter clash with New York’s state government over a mandate to banish its decades-old “Chief” logo, an illustrated side profile of a Native American man wearing a feathered headdress.

More than two years ago, the state’s Education Department required school districts to abandon mascots inspired by Native American culture or risk losing state funding. The order came amid a national effort to eliminate logos and nicknames that Indigenous people may find disrespectful.

But the ban led to a steep backlash across Nassau County, including in Massapequa, a middle-class swath of the South Shore where most residents voted for Mr. Trump in the November election. The town’s name is derived from a Native American term for “great waterland.”

The district’s five-member board of education swiftly denounced the prohibition, a Republican state senator proposed a legal carve out and students painted an enormous mural of the mascot near their high school in protest. School leaders argued in a federal lawsuit that the rule amounted to government overreach and a violation of the First Amendment.

The “Chief” name and logo are used across the district, including at Massapequa High School, though the school does not have a traditional costumed mascot, according to the school board.