Former director of national intelligence James Clapper issued a blunt warning on Sunday: President Trump is waging war on major U.S. institutions.

“I think, in many ways, our institutions are under assault, both externally — and that's the big news here, is the Russian interference in our election system — and I think as well our institutions are under assault internally,” Clapper said on CNN. Asked if he was referring to Trump, Clapper responded: “Exactly.”

It was a pretty striking allegation from the former top intelligence official — a man whose job, after all, was about identifying threats to the American government and homeland. (Dan Rather and GOP Sen. Ben Sasse of Nebraska made similar comments this weekend.)

It also happens to be true. Objectively so. And I'm not even sure Trump and the White House would quibble too much with Clapper's characterization.

Whether by frustration or design, the president has lashed out at a series of institutions and norms, from the press to the electoral system to the intelligence community to the judiciary to the longstanding rules of Congress to now, arguably, law enforcement. Some of these institutions are supposed to be insulated from politics — intelligence, the judiciary and law enforcement, specifically — but Trump has shown no qualms about attacking any thing or norm that runs afoul of him or stands in his way.

Post reporter Adam Entous explains what President Trump firing James Comey means for the investigation into Russia's alleged interference in the 2016 election. (Jason Aldag, Sarah Parnass/The Washington Post)

Some see this as a completely calculated effort by Trump to consolidate power. The more he damages the credibility of and faith in these institutions, the more they may be reluctant to challenge him, and the more his base will look to him as the only one who can save them. The press and intelligence community, in particular, are tasked with seeking the truth and providing objective facts on which policy decisions are made; Trump is arguing that they are too compromised and the only real truth is coming from his lips.

You don't have to look far to see op-eds and tweets noting that this is a strategy often employed by authoritarian leaders — leaders for whom Trump has done little to suppress his admiration. And it's valid to ask whether Trump has authoritarian goals or is just thin-skinned and willing to attack pretty much anything.

But if it is part of some broader strategy, Trump is exploiting an opening. Faith in American institutions has been declining for years, almost universally according to Gallup polling, as I wrote a couple of years ago.

Below are the percentages of Americans who have a "great deal" of confidence in each, since 1973:

At the time, a number of institutions had his 40-year lows — depths which have persisted through today:

Confidence is also at a historic low when it comes to organized religion (45 percent), the Supreme Court (30 percent), public schools (26 percent), newspapers (22 percent) and TV news (18 percent). And it's within a few points of an all-time low when it comes to banks (26 percent), organized labor (22 percent), the presidency (29 percent), the police (53 percent), the medical system (34 percent) and big business (21 percent).

In other words, people are running out of things to trust. And forward steps a big-talking presidential candidate — and now president — running against the political establishment, claiming to know everything about everything, and promising to Make America Great Again almost by sheer force of will. That's no coincidence.

And in his clashes with institutions, the GOP base has certainly been willing to take Trump's side. Republicans have by and large believed what Trump says more than the intelligence community when it comes to Russia's hacking and even when it comes to Trump's accusation that President Barack Obama wiretapped his campaign.

But there do seem to be limits to that. A Quinnipiac poll showed 4 in 10 Republicans doubted Trump's claim of Obama's wiretapping. And a new NBC News/Wall Street Journal poll shows 58 percent of Republicans think he did the right thing in firing FBI Director James Comey, with another 4 in 10 either disapproving (8 percent) or having no opinion (33 percent).

Trust in Trump also seems to be declining, even among Republicans. The latest Quinnipiac poll shows about 1 in 5 Republicans don't believe Trump is honest (21 percent) and believe the media more than him (17 percent). That's a small slice of the GOP, but there seem to be limits to the party's willingness to go along with whatever institution-busting crusade Trump embarks upon.

Keep watching those numbers; they'll tell the tale in the battle between Trump and the American institution.