Despite previous denials, it turns out that Jon Huntsman Sr., the father of the former presidential candidate, was Senate Majority Leader Harry Reid's source on the details of Mitt Romney's tax returns. That revelation surfaced in a New York Times write-up of a gossipy-sounding book on the 2012 elections. The book, Mark Halperin and John Heilemann's Double Down, also outlines how the Obama campaign secretly considered dumping Joe Biden for Hillary Clinton on the 2012 ticket. Biden, the Times explains, apparently comes off as "being overly consumed with his own political future" to some White House staffers. 

The Huntsman revelation refers to Harry Reid's statement in the heat of the 2012 campaign that he, citing a reliable but anonymous source, knew that Mitt Romney had not paid any taxes for about 10 years. Romney, as you'll remember, eventually released his returns from 2010 and 2011, but only under pressure. Here's the relevant bit from the Times story.  

The authors reveal the source who told Senator Harry Reid of Nevada, the majority leader, that Mr. Romney had not paid any taxes in 10 years: Jon M. Huntsman Sr., the father of Mr. Romney’s early rival in the Republican primaries.

And yes, this is a kind of surprising development. But it's only surprising because Huntsman Sr. flat-out denied that he was the source in 2012 for the damaging information on Romney. Until his denial, quite a lot of people thought that Huntsman the Senior fit the profile of Reid's mystery source pretty well, who was identified as a Republican with some connection to Bain Capital. Even though Huntsman was a longtime supporter of Romney, he called for the candidate to release a decade of his returns during the 2012 campaigns. Huntsman has personal ties to Reid, and is also connected to a longtime managing director at Romney's Bain Capital, according to a 2012 Washington Post story on Huntsman's denial. There's also the matter of a Huffington Post story on Romney's tax returns, co-bylined by Abby Huntsman. At the time of his denial, Huntsman had few kind words for the candidate (via the Post): 

“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 taxes 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.”

As the Times notes, Double Down doesn't sound particularly kind to former GOP candidate John Huntsman Jr., who served as the Obama administration's ambassador to China as he considered a run for president: Huntsman "assured top White House officials that he was not considering a Republican presidential bid," the Times writes, "even as he was meeting with potential campaign strategists during a trip to his Washington home around Christmas 2010."