Surely, now, we can concede that letting President Trump be Trump has exhausted itself — even among the smugly credulous.

For a year and a half, we’ve heard his supporters say: Watch what he does, not what he says. Sure, he’s rude and crude, they’ve said, but he’s going to make America great again.

No, he’s not.

Nor was he ever, notwithstanding a column I wrote just before Election Day, saying that America would survive no matter who won. My optimism was based solely on faith in the U.S. Constitution and the inherent checks and balances prescribed therein. To be wrong would mean that the checks aren’t being applied when imbalances occur.

We are there.

Trump, rather than holding a hard line with Russian President Vladimir Putin at their summit in Helsinki, essentially sided with the enemy by attacking U.S. intelligence and law enforcement agencies regarding their solidly conclusive finding that Russian hackers interfered with the 2016 presidential election. (Trump tried to backtrack Tuesday afternoon, saying that he does, in fact, accept the intelligence community’s findings on Russian meddling.)

The two leaders all but held hands during a news conference Monday as each dismissed the idea that Russia wants to undermine American democracy — and that special counsel Robert S. Mueller III’s investigation into possible collusion between Russian operatives and the Trump campaign has any legs to stand on. This despite Mueller having just this past Friday issued an indictment against 12 Russians believed to be involved in hacking the computer networks of Democratic organizations.

Are we to believe that these two known liars were telling the truth or hadn’t agreed to a script during their private, one-on-one meeting?

On Sunday, Trump, in his usual manner, blamed the Democrats for having a weak defense system against hacking. On Tuesday, he again waved the “fake news” flag, blaming the media for unfavorable summit coverage. The whole experience surely bonded him further with Putin, who favors a state-run media and rules a nation where journalists who become troublesome are often killed.

Between Trump’s antipathy toward the First Amendment, which he previously has expressed wishing to weaken — and his stated desire that “my people” sit up at attention when he speaks, as North Koreans did during his visit with Kim Jong Un — the president has made his dictatorial proclivities clear.

That said, such inclinations may more accurately reflect severe narcissism than a conscious desire to subjugate the American people. Given Trump’s paltry understanding of world affairs or his role as president, he quite possibly aligns himself with thugs as a means to man up, as they say, and correct some sense of impotence that persists despite his impressive success.

Consider Trump’s reply when challenged about his dubious posture toward American intelligence agencies: “I have great confidence in my intelligence people,” he said, “but I will tell you that President Putin was extremely strong and powerful in his denial today.”

Note “my” intelligence people, plus the obvious lie about confidence. And the words “strong,” “powerful” and “denial.” This is Trump in four words: self-absorbed, impressed by authority and at home in denial. This makes him easily unlikable to a majority of Americans but not necessarily treasonous, as some have charged out of proper outrage. Treason, frankly, sounds a little high-minded for such a reckless, clueless vaudevillian.

Where does this leave us? What might one deduce from the Helsinki summit? Either Trump is too thoroughly inept to continue as president, or his predatory nature, as demonstrated in his business — not to mention his boasting about aggression toward women — has led to his collecting rogues to enhance his own power. Or both. In any case, he has stepped over all lines of acceptable presidential behavior and presents a clear and present danger to the United States.

When our chief executive, whose principal job is to defend both the Constitution and the nation against aggressors, stands alongside our chief geopolitical foe and betrays two of our most important institutions in the service of his own ego, he has dimmed the lights in the shining city on a hill and left the world a far darker place.