“There’s a certain style of politics in Europe that believes: If you’re not with us, you’re against us,” said Michael Ignatieff, the university’s president and rector, who is also a human rights scholar and a former leader of the Liberal Party in Canada.

“The C.E.U. issue came to symbolize the amount of harm that some of the government’s actions are having right across the spectrum,” he added. “All we’re trying to do is get them to back off and leave us alone — and give us a guarantee that we can stay here.”

The law targeting Central European University injected fear and shock into the campus.

“This is an attack on academic freedom,” said Alexandra Medzibrodszky, 29, a Hungarian doctoral student in history, who was wearing a pin showing her support for the university. “This is why it resonates with intellectuals from all sides.”

Conservative scholars are among those who have spoken out.

“The entire academic sector of this nation, in essence, feels imperiled, following the passing of this law,” Miklos Kiraly, a law professor at Eotvos Lorand University in Budapest, wrote in an open letter after Mr. Orban asked why Hungarian scholars had been standing up for Central European University. “The general opinion is that there are no more boundaries, no more limits, no checks and sound professional considerations, consultations, traditions or acquired rights.”

Over the past quarter-century, the university has blended into the fabric of Budapest. Even English, the lingua franca around campus, stands out less in a city that has enjoyed a tourism boom and a building boom. Support for the university seems genuine — signs declaring “#IstandwithCEU” in English and Hungarian can be seen not only in university buildings but also in the windows of cafes and other businesses.