Thomas Friedman doesn't scare easily.

The New York Times op-ed columnist is best known for his sober columns about foreign policy and technology.

That's why his Monday column stood out. "Our democracy is in serious danger," he wrote in the opening line. "President Trump is either totally compromised by the Russians or is a towering fool, or both, but either way he has shown himself unwilling or unable to defend America against a Russian campaign to divide and undermine our democracy."

There was something about his last paragraph, in particular, that struck a chord. "This is code red," he wrote. "The biggest threat to the integrity of our democracy today is in the Oval Office."

Friedman's column lit up on social media when it was posted on NYTimes.com on Sunday night. Thirty six hours later, it is still No. 1 on the site's "most emailed articles" list. It is also No. 1 on the site's "most shared articles on Facebook" list. There have been more than 2,700 comments so far.

"That's a personal record," Friedman told CNN.

He said he was taken aback by the intensity of the reactions.

After all, his column normally appears in print on Wednesdays. This was just a bonus column for the web. He just felt compelled to write it after Trump went on a tweetstorm over the weekend.

"Not my day. Not in print. And it may be the most widely circulated column I've ever written," Friedman said.

He titled the column "Whatever Trump Is Hiding Is Hurting All of Us Now."

Friedman felt compelled to write it on Sunday morning while driving from Washington to Baltimore for a golf lesson. On the drive, he said he was thinking about Trump's Twitter reaction to the newest indictments in Robert Mueller's special counsel investigation.

He said "there was something in Trump's reaction to Mueller that was deeply off." He called it "so unpresidential, it was frightening."

Trump's erratic tweets had assailed the FBI, the media, Democrats -- but not Moscow. "To me, it really crossed a line," Friedman said. While Trump has "broken many norms as president," these tweets were different. "He's no longer violating norms of the presidency, he's actually violating his oath to defend and protect the Constitution."

"Mueller told us the core of our democracy -- our electoral system -- had been attacked by Russia," Friedman added. "And Trump was focused exclusively on what Mueller's report said, or did not say, about him."

So he emailed a paragraph-long pitch to Times op-ed editor Jim Dao and editorial page editor James Bennet -- saying he had to write a column, just for the web, to express himself -- something he's done from time to time. "Hey, go for it," was the response from the editors, he said.

Later in the day, back at home, he wrote the column in an unusually speedy two hours and ten minutes. "What I've learned as a columnist over the years is, when you write the right column at the right time, articulating a feeling that many people have but maybe didn't know quite how to express, you can get a big reaction," he said, adding, "This doesn't happen very often."

James Fallows of The Atlantic tweeted that the piece was "remarkable, and admirable." Frank Rich of New York magazine called it the "most uncompromising column of Tom Friedman's career."

David Corn of Mother Jones responded to Rich and said "Friedman is too late. Some of us have been saying this for a year and a half. Some of us warned of this before the election. Now he is merely stating the obvious."

But that's "what's interesting" about the column, Jim Edwards, founding editor of Business Insider UK, tweeted: "It simply describes the big picture in plain English, which many of us forget to do."