President Trump on Wednesday lashed out at the anonymous author of a New York Times op-ed who claimed to be part of a “resistance” effort within his administration, calling the piece “gutless” and calling for the newspaper to turn over the writer “for National Security purposes.”

The extraordinary op-ed, published online Wednesday afternoon, was written by a senior official in the Trump administration, according to the Times. It blasts Trump as morally unmoored, criticizes his “impetuous” leadership style and depicts a “two-track presidency” in which Trump acts according to his own whims while many of his top aides, in the author’s words, work to thwart his “more misguided impulses until he is out of office.”

In a tweet Wednesday evening, Trump wrote a single word: “TREASON?”

He later followed up with another tweet in which he called for the New York Times to hand over its source.

“Does the so-called ‘Senior Administration Official’ really exist, or is it just the Failing New York Times with another phony source?” Trump said in the tweet. “If the GUTLESS anonymous person does indeed exist, the Times must, for National Security purposes, turn him/her over to government at once!”

The statement fits in with Trump’s pattern of increasingly citing national security as a justification for his actions, some of which bear little connection to the issue.

In remarks to law enforcement officials in the East Room of the White House earlier Wednesday, Trump insisted that his administration is “doing a great job” and unloaded on the “failing New York Times” for running an “anonymous — meaning gutless — a gutless editorial.”

“Nobody has ever done in less than a two-year period what we’ve done,” he said. “So when you tell me about some anonymous source within the administration, probably who’s failing and who’s probably here for all the wrong reasons — no.”

The news outlet, Trump added, “probably wouldn’t even exist” without him.

“Some day, when I’m not president, which hopefully will be in about 6½ years from now, the New York Times and CNN and all of these phony media outlets will be out of business, folks, because there will be nothing to write and there’ll be nothing of interest,” the president said.

In a separate statement, White House press secretary Sarah Huckabee Sanders called the op-ed “a new low” for the New York Times and suggested that the news outlet should issue an apology.

“We are disappointed, but not surprised, that the paper chose to publish this pathetic, reckless, and selfish op-ed,” Sanders said.

She also called on the op-ed’s author to resign from the administration.

“The individual behind this piece has chosen to deceive, rather than support, the duly elected President of the United States,” Sanders said. “He is not putting country first, but putting himself and his ego ahead of the will of the American people. This coward should do the right thing and resign.”

Secretary of State Mike Pompeo also spoke out against the author of the piece, telling reporters in India on Thursday: “It is sad that you have someone who would execute that choice.”

Pompeo, who said he did not write the piece, blamed its publication on a media that he said is trying to undermine Trump, a phenomenon he called “incredibly disturbing.”

In addition to painting a dire picture of Trump’s decision-making process, the op-ed also states that some top administration officials discussed early on in Trump’s presidency whether to seek to remove him from office via the 25th Amendment.

“Given the instability many witnessed, there were early whispers within the Cabinet of invoking the 25th Amendment, which would start a complex process for removing the president. But no one wanted to precipitate a constitutional crisis,” the op-ed reads. “So we will do what we can to steer the administration in the right direction until — one way or another — it’s over.”

Trump’s “treason” remark prompted criticism from some members of his own party.

In an interview with CNN, Sen. Lindsey O. Graham (R-S.C.), who has emerged as one of Trump’s most vocal defenders, described the letter as a “disloyal and cowardly act towards the president” but said it fell short of treason.

To those who think the president is unfit to serve, Graham said: “You don’t know what you’re talking about.”

John Wagner contributed to this report.