Hanover — Student activists at Dartmouth College have run up against a new obstacle in their campaign to end the use of the word “illegal” to describe undocumented immigrants: Republicans in the U.S. Congress.

Dartmouth students this spring helped persuade the Library of Congress to abandon “illegal alien” as a term for noncitizens who are not legal residents, saying it encourages racial discrimination.

But Republican legislators now are fighting back, arguing the change is “political correctness” and obscures the fact that some immigrants are here in violation of U.S. laws.

“My constituents know that illegal immigration by any other name is still illegal, and we should identify it as such,” U.S. Rep. Diane Black, R-Tennessee, said in a statement accompanying a piece of legislation that would block the library’s decision. “That is why my bill directs the Library of Congress to continue using the term ‘illegal alien’ just as they were previously.”

The story begins with a group of Dartmouth students who formed a network to support undocumented immigrants on campus.

While researching in the college library, the activists noticed that Dartmouth categorizes some of its books using the term “illegal alien” — a descriptor that implies that some people, not just their acts, are unwelcome, the activists say.

The students asked administrators to change the header, only to learn that their library — and most others in the English-speaking world — takes direction from the Library of Congress.

After months of petitioning the nation’s largest repository of knowledge, the students — with help from the influential American Library Association — succeeded.

The Library of Congress in March announced it would remove “illegal alien” and replace it with two headers: “unauthorized immigrant” and “noncitizen.”

Congressional Republicans, for their part, also argue that this change could interfere with legal research, where many source documents still use the terms “illegal” and “alien.”

“Scholars of immigration, sociology, and other related disciplines will now face increased research barriers, as will jurists seeking to access your historical materials in order to understand the historical landscape of immigration law,” said a letter from four legislators, including Sens. Jeff Sessions, R-Ala., and Ted Cruz, R-Texas, to the Library of Congress.

But Oscar Cornejo Casares, a rising senior at Dartmouth who helped found the student group, says they are missing the point.

“I’m really hoping that we go past the legal aspect of this,” he said in a Tuesday interview. “They don’t understand the cultural or linguistic connotations that go with this terminology.”

House Democrats expanded on Casares’ argument during a floor debate this month.

U.S. Rep. Debbie Wasserman Schultz, D-Fla., accused the Republicans of politicizing the librarians’ expert decision and defending language that had become racially charged and pejorative.

“This language is not necessary, it is not appropriate, and it jeopardizes the work of our nation’s oldest federal cultural institution and the research arm of this body,” she said. “The Library of Congress makes thousands of changes to its subject headings every year. At one time, ‘Negro’ was a subject heading, but when it became pejorative, they changed it to ‘Afro American,’ and eventually (to) the term used today, ‘African American.’ ”

In a letter to House lawmakers, the American Library Association pointed out that many major news organizations have stopped using “illegal” to describe people, and urged them to stand down.

Beyond “Negro,” the ALA’s letter said, “The catalog term ‘Cripples’ similarly morphed over time, first to ‘Handicapped’ and later to ‘People with disabilities.’ Congress made no move to countermand those expert cataloging determinations.”

Nevertheless, Black’s proposal passed the Republican-led House as a rider to a spending bill, and now is before the Senate.

The higher chamber’s version of the appropriations bill currently does not include Black’s provision, and if it passes without such language, it might have to be reconciled in a conference committee.

How that will go is anyone’s guess, and federal legislators from the Upper Valley appear to be mixed in their views.

Spokespeople for U.S. Sens. Jeanne Shaheen, D-N.H., and Patrick Leahy, D-Vt., as well as U.S. Rep. Peter Welch, D-Vt., said the lawmakers supported the students’ measure.

But U.S. Rep. Annie Kuster, D-N.H., is still studying the issue, a spokesperson said, as is U.S. Sen. Kelly Ayotte, R-N.H.

Legislators have found other ways to support the Library of Congress’ change.

U.S. Rep. Joaquin Castro, D-Texas, has introduced a bill that would remove the term “illegal alien” from U.S. legal code, neutralizing the argument that the library’s move would be inconsistent with statute.

But his legislation would have to make its way through a Republican-controlled House, the same chamber that passed Black’s bill.

Rob Wolfe can be reached at rwolfe@vnews.com or 603-727-3242.