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

For a year and a half, we’ve heard his supporters say, essentially: “Watch what he does, not what he says. Sure, he’s rude and crude, 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 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.

President 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. (The next day, Trump said that he does, in fact, accept the intelligence community’s findings on Russian meddling; more recently, he backtracked on his backtracking, calling interference reports “a big hoax.”)

The leaders all but held hands during a news conference July 16 as each dismissed the idea that Russia wants to undermine American democracy – and declared that Robert Mueller’s investigation into possible collusion between Russian operatives and the Trump campaign has no legs to stand on. This despite Mueller having just issued 12 indictments against 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 July 15, Trump, in his usual manner, blamed the Democrats for having a weak defense system against hacking. On July 17, 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 a narcissistic personality disorder 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.

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.

Where does this leave us? 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.

My faith in the institutions and the individuals who conferred upon us a singular role in the history of humankind is yet unshaken. But a cancer lives among us, and the good people of this country must be precise in its excision. If Republicans don’t do it now, Democrats likely will sweep the ballots in November and do it then.

History will note when, and by whose hand, America ceased to be great.

Kathleen Parker is a columnist for The Washington Post. She can be contacted at:

kathleenparker@washpost.com