President Trump fired Carla Hayden as the librarian of Congress on Thursday, sparking the ire of congressional Democrats who said he was ousting a groundbreaking professional from a critical nonpartisan job.

Members of Congress confirmed the firing on social media.

“This is disgraceful,” said Sen. Ed Markey, a Massachusetts Democrat who said his “dear friend” was fired by email.

The Library of Congress serves as a repository of books and documents, preserves important parts of America’s history and operates as Congress’s research branch.

While the position is closely attached to Congress, it is nominated by the president, which also makes it subject to firing. Some lawmakers vowed to change that in the wake of Ms. Hayden’s ouster.

Ms. Hayden, the first woman and first Black person to hold the job, was tapped by President Obama to a 10-year term in 2016.

Senate Minority Leader Charles E. Schumer, New York Democrat, said Ms. Hayden’s firing was an attack on “the guardrails of our democracy.”

“That she is being ousted by a man who knows more about sowing division than preserving knowledge is an insult not only to her but to every American who values facts, history, and truth,” Mr. Schumer said.

• Stephen Dinan can be reached at sdinan@washingtontimes.com.