The Washington Post’s Bob Woodward. (JIM WATSON/AFP/GETTY IMAGES)

Only in Washington does a tempest turn on the meaning of the word “regret.”

Only in Washington does the back-and-forth between a legendary journalist and a White House wonk turn into an epic talking-head fest and trending Twitter topic.

And only in Washington does a sideshow to a looming economic calamity become the show itself.

It all came together like a NASCAR pileup on Thursday as the politerati and the digerati and actual regular people hashed out the who-shot-whom dynamics of Bob Woodward’s jeremiad against the White House.

Woodward, chronicler of presidents since the Watergate era (which might not have been an era without his reporting), pushed back against a White House challenge to his claim in a Sunday Washington Post op-ed that President Obama and his budget negotiators had come up with the idea of the sequester and had “moved the goal posts” in talks with Republicans by insisting on new taxes.

That characterization bought Woodward a heated lecture from Gene Sperling, Obama’s top economic adviser, who told him the following in a subsequent e-mail: “I do truly believe you should rethink your comment about saying . . . that [Obama] asking for revenues is moving the goal post. I know you may not believe this, but as a friend, I think you will regret staking out that claim.”

In an interview Wednesday with Politico, it sounded like war; indeed, the headline was “Woodward at War,” a play on the title of one of his best-selling books about President George W. Bush.

Politico excerpted Sperling’s e-mail, trimming the “I know you may not believe this, but as a friend” part, and suggested Woodward didn’t take kindly to Sperling’s admonition.

Politico wrote: Woodward repeated the last sentence [of Sperling’s e-mail], making clear he saw it as a veiled threat. “ ‘You’ll regret.’ Come on,” he said. “I think if Obama himself saw the way they’re dealing with some of this, he would say, ‘Whoa, we don’t tell any reporter you’re going to regret challenging us.’ ” (Actually, the Obama press shop has quite a reputation for playing hardball and has been known to deploy a few four-letter words with reporters.)

Woodward said he stands by the idea that Sperling’s language was over the line but stops short of suggesting outright intimidation. “I never characterized it as a ‘threat,’ ” he said. “I think that was Politico’s word. I said I think [Sperling’s] language is unfortunate, and I don’t think it’s the way to operate. . . . [Sperling’s] language speaks for itself. I don’t think that’s the way to operate.”

Politico said it stands by its reporting.

(And if you’re a fan of inside baseball, don’t even get started on the political-media daisy chain and incest fest at work here: that is, Woodward first spouted off in The Post, then spouted off further to two Politico reporters, Mike Allen and Jim VandeHei, who used to work with Woodward at The Post, whose reporter now is following up the Politico article by quoting Woodward about a story initiated by Woodward himself.)

In an interview with CNN on Wednesday night, Woodward never used the word “threat” or said that he felt threatened. But he said Thursday: The White House has “the power. When someone says ‘you’ll regret something,’ they can use their power any way they want. It’s a tone question. . . . I’ve been dealing with White House people going back to the Nixon years. They called us every name in the book. [This] just strikes me as not a way to deal with this. It makes me uncomfortable.”

In a statement, the White House said that as “Mr. Woodward noted, the email from [Sperling] was sent to apologize for voices being raised in their previous conversation. The note suggested that Mr. Woodward would regret the observation he made regarding the sequester because that observation was inaccurate, nothing more. And Mr. Woodward responded to this aide’s email in a friendly manner.”

One of the ironies of this little flap is that Woodward — long savaged by the right for his reporting on Republicans, starting with Richard Nixon — is getting attaboys from conservatives for standing up to all of this president’s men. Woodward says there’s nothing amusing or ironic in that; he’s just going where the facts are taking him.

In fact, it’s the Democrats now taking shots at Woodward. “Watching Woodward last 2 days is like imagining my idol Mike Schmidt facing live pitching again,” tweeted David Plouffe, Obama’s former adviser. “Perfection gained once is rarely repeated.”

As for the fireworks the story set off, Woodward is amused. Just a little.

“People out in the non-Washington world, because of the nature of gridlock and not fixing things in Washington, this is a source of total wonder to them,” he reckons. “In a way, the biggest story in this town is about the town itself. People wonder what’s going on here. And every now and again, you get another example of how things operate.”