WASHINGTON — Scary question of the day: If this is how President Trump reacts to news of a federal grand jury being employed in the Russia investigation, what happens if things turn really serious?

Reports that special counsel Robert Mueller is using a grand jury to collect evidence reaffirmed what was already obvious to legal observers: This probe — and for the president, this problem — is not going away anytime soon.

Mueller is beefing up his staff, bringing in former federal prosecutors with experience in complex financial investigations. Of course there is a grand jury.

That’s how prosecutors do their work, unless they have come to the quick conclusion that the subject is a dry hole. This was never likely in Mueller’s case, and every week seems to open a new and potentially productive avenue for him to follow.

So White House special counsel Ty Cobb had the right response to the grand jury news. “The White House favors anything that accelerates the conclusion of his work fairly,” he said in a statement. “The White House is committed to fully cooperating with Mr. Mueller.”

Restrained. Appropriate. Normal.

Not so the president.

Once again, he diminished the significance of Russian efforts to interfere in the 2016 election and demeaned the findings of the U.S. intelligence community: “The Russia story is a total fabrication. It is just an excuse for the greatest loss in the history of American politics.”

Once again — as the West Virginia crowd chanted “Lock her up!” — he said the focus should be on his vanquished opponent, not him: “What the prosecutor should be looking at are Hillary Clinton’s 33,000 deleted emails. And they should be looking at the paid Russian speeches. And the owned Russian companies. Or let them look at the uranium she sold that is now in the hands of very angry Russians.”

Even leaving aside the factual flimsiness of Trump’s accusations, the inappropriateness of a sitting president making this argument is impossible to overstate. As his still-Attorney General Jeff Sessions told the Senate Judiciary Committee in January, “This country does not punish its political enemies.”

This country also has mechanisms, well-honed and well-tested, for dealing with situations where criminal investigations are warranted. They require recusal in cases that pose a clear conflict of interest, as Sessions recognized in immediately walling himself off from any Clinton investigation and eventually accepted in recusing himself from the Russia probe.

They set out procedures for the White House to follow in dealings with the Department of Justice involving criminal proceedings, designed, as then-Attorney General Eric Holder explained, to ensure that prosecutors are “impartial and insulated from political influence.”

Such niceties are not for Trump. No surprise there, but the worst of his West Virginia speech was yet to come. Trump followed by impugning the Mueller investigation as an illegitimate effort to undo the election results: “They can’t beat us at the voting booths, so they’re trying to cheat you out of the … future that you want. They’re trying to cheat you out of the leadership that you want with a fake story that is demeaning to all of us, and most importantly demeaning to our country and demeaning to our Constitution.”

Trademark Trump. He takes the very thing that he is doing — in this case, demeaning the Constitution — and flings that accusation back at his opponent. Trump’s campaign and now his presidency have been an unceasing effort to demean the Constitution. From “fake news” to “so-called” judges, from his ill-considered travel ban to encouraging police officers’ roughing up of suspects, Trump is a one-man assault on the rule of law.

Inciting supporters to equate a criminal investigation (and potential prosecution) with a usurpation of their democratic choice is the most chilling yet. What Trump decries as a witch hunt is an authorized investigation being conducted pursuant to Justice Department rules, by an experienced prosecutor, selected for this job by another experienced prosecutor, who was nominated by Trump himself. That Trump and his allies are scheming to undermine Mueller’s legitimacy underscores that their sole goal is retaining power, the law be damned.

Some readers have asked a fair and important question: Why is nearly every column of mine about Trump? The answer is: Trump. His behavior is so extreme and so dangerous that to respond only episodically and occasionally is to risk allowing it to appear acceptable. Outrageous words and outrageous actions require expressions of outrage in return, each and every time. That will continue until the danger subsides.

Ruth Marcus’ email address is ruthmarcus@washpost.com