Washington — The rhetorical intensity of Donald Trump’s anti-impeachment campaign, measured on a scale of one to 10, has begun at 11.25. The whistleblower is “almost a spy” who may be guilty of “treason.” House Intelligence Committee Chairman Adam Schiff, D-Calif., should be arrested for “treason.” Both are part of a “COUP” which — if successful — could provoke a “civil war.”

How is it possible to escalate any further from here? What is the step beyond the threat of political violence?

The willingness of elected Republicans to follow Trump in the scorched-earth defense of his power is a sign that the old GOP — defined by deference to institutions — is well and truly dead. It is one thing to reflect Trump’s vicious, partisan tone; it is another to accept that portions of the American government, including some in the FBI and CIA, are part of a conspiracy to overthrow the president. Smarmy sycophants such as House Minority Leader Kevin McCarthy, R-Calif., have joined in Trump’s allegation of a “coup” — indifferent to the institutional wreckage such a charge will leave behind.

In the White House, and in the conservative fever swamps, the message is now the same. “The ongoing effort to undermine and remove a duly elected president,” says columnist Monica Crowley, “is a rolling deep state coup d’état (with an assist from the media), making it the most dangerous scandal in American history.” Political activist David Bossie alleges a “vast left-wing conspiracy that began with Crossfire Hurricane, the Clinton Campaign and the Democratic National Committee.” The conspiracy-minded wing of the GOP is suddenly ascendant, and former Texas Rep. Ron Paul can hardly contain himself. “It’s hard not to ask whether this is a genuine impeachment effort … or a CIA coup!”

Is this something more than metaphorical excess? Unfortunately, it seems to be. Recent revelations show that Trump is a true believer in a truly balmy theory. He is convinced that Australian and American spies — working with other elements of the American deep state, and somehow with Great Britain and Ukraine — laid the fraudulent groundwork for the Mueller investigation, in the hope of overturning the result of the 2016 election. This conspiracy theory is what Trump asked Ukraine President Volodymyr Zelensky to investigate, and what Trump asked Australian Prime Minister Scott Morrison to investigate, and what Trump asked British Prime Minister Boris Johnson to investigate.

Zelensky was also asked (as Trump has now asked China) to investigate former Vice President Joe Biden and his son Hunter. This had the narrow (and highly unethical) purpose of gaining advantage over a political rival.

But it is this broader theory concerning the origins of the Mueller probe that seems to captivate Trump and Attorney General William Barr. Long before he was appointed to his office, Barr said the Mueller investigation risked “taking on the look of an entirely political operation to overthrow the president.” In April, Trump told Fox News’ Sean Hannity that Barr was examining “big” and “incredible” proof that Ukraine had cooperated with Hillary Clinton to plant evidence against him.

Trump’s series of calls to foreign leaders sought evidence to undermine the credibility of the Mueller investigation — and, in the case of Ukraine, urged its leader to work with Barr to expose the plot. What cooperation was given? What information was provided? The impeachment investigation will presumably ask and answer such questions.

But what is frightening, and undeniable, is that Trump is not just employing conspiracy theories as part of a propaganda campaign. He actually believes them. He seems convinced that an intelligence cabal — involving two of America’s closest allies — sought to overturn his election as president. This would indeed be a dangerous scandal — if it were even remotely true.

The real danger lies in an American president operating in a dream world where he is in a heroic struggle against enemies who conduct coups and might require armed resistance. What measures might be required to confront that kind of national emergency? How far will Trump go to root out the authors of treason and subversion?

Consider a recent Trump tweet in this light: “As I learn more and more each day, I am coming to the conclusion that what is taking place is not an impeachment, it is a COUP, intended to take away the Power of the People, their VOTE, their Freedoms, their Second Amendment, Religion, Military, Border Wall, and their God-given rights as a Citizen of the United States of America!”

It is hard to escape the undertone of menace.

— Michael Gerson is a columnist for Washington Post Writers Group.