Before President Trump chastised Gov. Janet Mills of Maine at the White House last month, and before his administration started investigating Maine’s education system, the seeds of their conflict over transgender athletes had been planted by a state legislator.

Representative Laurel Libby, a Republican from Auburn, Maine, had posted on Facebook about a transgender athlete who won a high school pole-vaulting competition. Her critical post, which named and included photos of the student athlete, went viral.

About a month later, the fallout has included funding cuts at the University of Maine and a finding by the Trump administration that the state had violated federal law by allowing transgender athletes to compete on two high school teams. The Democratic-controlled Legislature has censured Ms. Libby. And people on both sides of the issue have experienced a complex surge of emotions about Maine suddenly landing in the cross hairs of Mr. Trump.

“We’re not often in the center of controversy here, and it’s a little bit of a shock that it’s happened so quickly,” said Keegan Tripp, a junior at the University of Maine and the president of its student body. “We have students afraid for themselves, for their friends — their academics, research, financial situations — and all of this fear is so brand-new.”

When the Trump administration issued an executive order on Feb. 5 barring transgender women from women’s sports, Ms. Libby, a 43-year-old mother of five, saw an opportunity to amplify her own position on the matter.