An unnamed senior Trump official has said members of the administration are working to frustrate parts of the president's agenda to protect the country from his "worst inclinations".
In a New York Times editorial, the author said President Trump's "amorality" and "impulsiveness" had led to ill-informed and reckless decisions.
Mr Trump labelled the anonymous writer "gutless" and the newspaper as "phony".
His press secretary said the mystery writer was a "coward" who should quit.
The Times defended the editorial in a statement, saying: "We are incredibly proud to have published this piece, which adds significant value to the public's understanding of what is going on in the Trump administration."
The opinion piece comes a day after excerpts of Bob Woodward's book on the Trump White House suggested that his top officials have been engaged in an "administrative coup d'etat" to protect the nation from the president, including removing key documents from his desk before he has a chance to sign them.
This, then, presents itself as first-hand acknowledgement that the coup is real.
The author says that he/she isn't a liberal operative and agrees with many of the policy goals the administration is pursuing, but that those goals are being achieved in spite of - and not because of - the president.
What does the senior official say about Trump?
The laundry list of criticisms should be familiar to the president's opponents on the left and the right, however. Disorganised meetings, an impetuous and petty demeanour, an inability to stick to decisions, antipathy to a free press and "anti-democratic" instincts.
"Many of the senior officials in his own administration are working diligently from within to frustrate parts of his agenda and his worst inclinations," the author writes.
"I would know. I am one of them."
"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."
He/she describes a "two-track presidency", where the president's actions - such as his conciliatory attitude toward "autocrats and dictators", including Kim Jong-un and Vladimir Putin - are constrained and redirected by "adults in the room".
"This isn't the work of the so-called deep state," the author writes. "It's the work of the steady state."
What's more, the author says that some in the administration have whispered about invoking the 25th Amendment, a constitutional provision that allows the vice-president and a majority of the Cabinet secretaries to vote to remove a president who is "unable to discharge the powers and duties of his office".
Such a manoeuvre has been, up until now, largely consigned to the fringes of American political discourse and the fever dreams of Mr Trump's angriest opponents.
"No-one wanted to precipitate a constitutional crisis," he/she writes. "So we will do what we can to steer the administration in the right direction until - one way or another - it's over."
How has the White House responded?
There has already been talk of an aggressive push within the White House to find out the identity of the sources Woodward relied on for his book, Fear: Trump in the White House. The Times essay is throwing fuel on an already raging fire.
Mr Trump took to Twitter with a simple word: "TREASON?"
He followed it up with a tweet questioning whether the official actually existed or had been made up by the Times. He added: "If the GUTLESS anonymous person does indeed exist, the Times must, for National Security purposes, turn him/her over to government at once!"
He added another tweet later, saying: "I'm draining the Swamp, and the Swamp is trying to fight back. Don't worry, we will win!"
White House press secretary Sarah Huckabee Sanders sent out a sharply worded official response.
"The individual behind this piece has chosen to deceive, rather than support, the duly elected president of the United States," she writes. "He is not putting country first, but putting himself and his ego ahead of the will of the American people."
On Thursday, Secretary of State Mike Pompeo, who is in India, attacked the New York Times for choosing to publish "a disgruntled, deceptive, bad actor's word", adding: "It's sad."
He said: "I find the media's efforts... to undermine this administration incredibly disturbing."
Amid social media speculation that Vice-President Mike Pence might be the author of the piece, his communications director, Jarrod Agen, tweeted that the vice-president "puts his name on his Op-Eds".
Mr Agen added: "The @nytimes should be ashamed and so should the person who wrote the false, illogical, and gutless op-ed. Our office is above such amateur acts."
Guessing game - who is the anonymous source?
Outside of the administration, the essay will set off one of Washington's favourite games - guessing the identity of an unknown author. Not since "Anonymous" wrote the novel Primary Colors, a thinly disguised fictional account of the 1992 Bill Clinton presidential campaign, has there been a mystery like this. Primary Colors was later revealed to have been written by journalist Joe Klein.
Given that much of the focus of the piece is on conduct in international affairs, the spotlight will probably shine the brightest on the president's foreign policy team - in the Department of State, National Security Council and Department of Defense.
There will also surely be calls for this administration official to reveal him/herself."The crisis of our time is that people in positions of power see a president who shows 'a preference for autocrats and dictators' and 'anti-democratic impulses', but do not publicly stand against them, and so allow it to continue," tweets Congressman Don Beyer of Virginia.
An anonymous confession that only confirms the fears of Mr Trump's critics is hardly a profile in courage. Following so quickly on the heels of the Woodward book, however, the New York Times essay will make for a one-two punch that will be difficult to shake off.