I’m shocked — not that the Huntsmans would knife Romney in the back but that Reid would have the minimal integrity to actually base his smear on something that someone told him. I was a thousand percent sure that he’d made up the “Romney doesn’t pay taxes” thing whole cloth for funsies, to make Romney sweat at a moment when Democrats were pressing him on the issue. Let it be noted for the record, then: He may be an absolute A-hole but Harry Reid’s not in the habit of falsely accusing people of wrongdoing unprompted. It takes at least a modicum of prompting to get him to make that false accusation.

The important question now: This isn’t going to derail the Huntsman 2016 express, is it?

The source of Senate Majority Leader Harry Reid’s (D-NV) infamous claim during the 2012 presidential campaign that Mitt Romney had not paid any taxes in 10 years was Jon Huntsman Sr., the father of fellow GOP rival Jon Huntsman, according to a new book by Mark Halperin and John Heilemann called “Double Down.”

Reid bashed Romney with the claim, which he said came from a Republican and a Bain Capital investor, during the summer of 2012 as the former Mass. governor repeatedly refused to disclose the tax documents.

Huntsman Sr denies it, saying, “These fellows who wrote this book, they dwell on falsehoods and false rumors. They’re nothing but supermarket, tabloid trash. They ought to be ashamed of themselves.” He was, however, a suspect from the beginning, partly because he’s friends with Reid, partly because he’s partners with a former Bain Capital director (Reid claimed his source was a Bain investor), and partly because, despite his support for Romney after his son dropped out, Huntsman’s relationship with Romney has been intermittently chilly over the years. This WaPo piece from early 2011 chronicles the sporadic nastiness, from Huntsman Sr complaining after Mitt had won the job to take over the 2002 Olympics that he was “politically driven” and “very, very slick and fast-talking” to Huntsman Jr earning Romney’s wrath in 2006 by endorsing McCain after allegedly promising his support to Romney. Huntsman Sr’s wife told WaPo flat-out at the time that she wouldn’t support Romney if he ran for president for reasons she refused to specify. Huntsman Jr played rough with him at different points during the campaign too, once dismissing him as being in “the hip pocket of Wall Street.” Go figure that Huntsman Sr fell under suspicion.

In fact, here’s what he told Greg Sargent last year when he first denied that he was Reid’s source. Does this sound like a man who’d badmouth Mitt Romney behind his back?

“I feel very badly that Mitt won’t release his taxes and won’t be fair with the American people,” Huntsman told me. In a reference to Romney’s father, who pioneered the release of returns as a presidential candidate, Huntsman said: “I loved George. He always said, [release] your [tax returns] for at least 10 or 12 years.”…

“Mr. Romney ought to square with the American people and release his taxes like any other candidate,” Huntsman said. “I’ve supported Mitt all along. I wish him well. But I do think he should release his income taxes.”

To think: If not for Reid’s mystery source and the smear that he propagated, Romney might have won … a few hundred more votes, maybe? Meh.

Here’s Abby Huntsman, Jon Jr’s daughter and new co-host of “The Cycle,” encouraging Romney’s son to primary Mike Lee in Utah because, I guess, even a Romney is better than a conservative. Exit fun fact: When Jon Jr dropped out of the race early last year, he complained that it had “degenerated into an onslaught of negative and personal attacks.”