The US president is acting in a manner that is "detrimental to the health of our republic", an anonymous senior official wrote in The New York Times on Wednesday, with Donald Trump terming it "treason" and "gutless".
In the op-ed titled "I Am Part of the Resistance Inside the Trump Administration", the official said he and like-minded colleagues have vowed to thwart parts of the president's agenda and his worst inclinations.
President Trump is facing a test to his presidency unlike any faced by a modern US leader, claimed the writer, who The New York Times, in a tweet, identified as a he.
The daily, which rarely publishes anonymous articles, said it did not disclose the name of the senior official in the Trump administration on the request of the author, whose "identity is known to us and whose job would be jeopardised by its disclosure".
The official said, "To be clear, ours is not the popular 'resistance' of the left. We want the administration to succeed and think that many of its policies have already made America safer and more prosperous."
"But we believe our first duty is to this country, and the president continues to act in a manner that is detrimental to the health of our republic.
"That is why many Trump appointees have vowed to do what we can to preserve our democratic institutions while thwarting Mr Trump's more misguided impulses until he is out of office," the writer said.
However, Donald Trump, speaking to reporters at the White House, lashed out at the daily, saying that "anonymous, meaning gutless, editorial."
"When you tell me about some anonymous source within the administration, probably who is failing and probably here for all the wrong reasons, and The New York Times is failing. If I were not here, I believe The New York Times probably would not exist," he said.
"We have somebody in what I call the failing New York Times that is talking about, he is part of the resistance in the administration. This is what we have to deal with," President Trump said.
In a tweet he demanded the New York Times reveal the identity of the person.
"Treason? Does the so-called senior administration official really exist, or is it just the Failing the New York Times with another phony source? If the gutless anonymous person does indeed exist, the Times must, for National Security purposes, turn him/her over to government at once." Donald Trump said on Twitter.
TREASON?- Donald J. Trump (@realDonaldTrump) September 5, 2018
Does the so-called "Senior Administration Official" really exist, or is it just the Failing New York Times with another phony source? If the GUTLESS anonymous person does indeed exist, the Times must, for National Security purposes, turn him/her over to government at once!- Donald J. Trump (@realDonaldTrump) September 5, 2018
In the damaging editorial, the official alleged that in public and in private, Donald Trump showed preference to autocrats and dictators such as Russian President Vladimir Putin and North Korean leader Kim Jong-un, and displayed little genuine appreciation for ties that bind the US to allied and like-minded nations.
He said though Donald Trump was elected as a Republican, "the president shows little affinity for ideals long espoused by conservatives: free minds, free markets and free people".
The official said at best, Mr Trump has invoked these ideals in scripted settings and at worst, he has attacked them outright.
"In addition to his mass-marketing of the notion that the press is the enemy of the people, President Trump's impulses are generally anti-trade and anti-democratic," he said.
From the White House to the executive branch departments and agencies, senior officials will privately admit their daily disbelief at the commander in chief's comments and actions, the writer claimed. "Most are working to insulate their operations from his whims."
The official said, "Astute observers have noted, though, that the rest of the administration is operating on another track, one where countries like Russia are called out for meddling and punished accordingly, and where allies around the world are engaged as peers rather than ridiculed as rivals.".
The White House has called for the resignation of the senior administration official who wrote the piece.
"The individual behind this piece has chosen to deceive, rather than support, the duly elected president of the United States.
"He is not putting the 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," White House Press Secretary Sarah Sanders said.
Nearly 62 million people voted for Trump in the 2016 elections, earning him 306 electoral college votes against 232 for his opponent. None of them voted for a "gutless, anonymous source to the failing New York Times," she said.
"We are disappointed, but not surprised, that the paper chose to publish this pathetic, reckless, and selfish op-ed.
"This is a new low for the so-called 'paper of record', and it should issue an apology, just as it did after the election for its disastrous coverage of the Trump campaign," Ms Sanders said.
This is just another example of the liberal media's concerted effort to discredit the president, she claimed.
The senior administration official also said 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. So we will do what we can to steer the administration in the right direction until one way or another it is over," the official said.
"The bigger concern is not what Mr Trump has done to the presidency but rather what we as a nation have allowed him to do to us. We have sunk low with him and allowed our discourse to be stripped of civility," he wrote.