Successful political campaigns are often tight-lipped enterprises, with those involved bottling up unflattering details to insulate candidates from fallout — and for good reason, given the unseemly rivalries that can flourish in the heat of a presidential race.

Once elections are in the books, though, all the seedy backroom details have a way of leaking out into, well, more books.

Such is the case with Double Down, Mark Halperin and John Heilemann's forthcoming postmortem on the 2012 election. Though the sequel to the duo's bestselling book on the 2008 campaign, Game Change, won't be released until next week, the New York Times' Jonathan Martin got a look at an advance copy and pulled out some great details.

Among them:

Bye, bye Biden
Members of President Obama's inner circle seriously considered booting Biden from the ticket and replacing him with then-Secretary of State Hillary Clinton.

That crazy-sounding idea was floated at various points during the election, though Team Obama shot it down every time. Back in the summer of 2011, for instance, scattered reports claimed that Obama, mired in a polling slump, might tap New York's popular Gov. Andrew Cuomo as his number two. And mere months before the election, Sen. John McCain (R-Ariz.) said it would be "wise" for Obama to dump Uncle Joe.

Despite the Obama campaign's denials, though, the book claims top aides conducted focus groups and polls to see if a change would give Obama an extra edge. In the end, they decided any benefit wasn't worth the risk of such a jaw-dropping upheaval. Obama's former Chief of Staff William M. Daley told the Times the campaign did look at adding Clinton to the ticket, but said it was merely "due diligence," and never a serious plan.

The revelation came out the same day Politico reported that Obama asked Clinton to stay on with the administration for one more year. Clinton declined, and left the State Department at the end of January.

Christie's health history
Gov. Chris Christie (R-N.J.) was seen by many as a good choice to complement Mitt Romney. He had broad bipartisan appeal and a conservative track record, both of which Romney could have used. (In Rep. Paul Ryan (R-Wisc.) he got the latter, but not so much of the former.)

Yet Romney nixed Christie, according to the book, because of concerns about his health and background. Christie, who is widely believed to have his eye on the top slot on the ticket anyway, underwent lap band surgery earlier this year to get his weight under control. The governor also, according to the book, did not answer the Romney camp's inquiries about his potential political soft spots — like a defamation suit earlier in his career — in nearly the same detail as other potential veeps.

Christie would later enrage Republicans by lauding Obama for his cooperation on Hurricane Sandy, so maybe it was a good thing Christie didn't get the VP nod after all. That would have been awkward.

Bill and Barack's tense relationship
It's no secret that Obama did not always get along too well with the Clintons. There was no love lost after their titanic struggle during the 2008 Democratic primary, and though Hillary's State Department appointment was considered something of a peace offering, the relationship between Bill and Obama never really healed.

While the former president stumped for Obama and delivered a rousing convention speech, before that their relationship was chilly. They couldn't even get through a full round of golf, according to the book, with Obama later telling an aide he only liked Clinton "in doses."

As the campaign heated up though, and Obama looked vulnerable, the president increasingly sought Clinton's help and advice. After Obama's horrible showing in the first presidential debate, he reportedly brought in Clinton to help him strategize. And right after taking Romney's concession call on Election Night, he told his campaign manager, "Get Bill on the phone."

The Huntsmans' sneaky dealings
Remember when Majority Leader Harry Reid said he had learned that Romney hadn't paid taxes in a decade? And remember how infuriated Republicans repeatedly demanded that Reid back up his statements, only to be stonewalled by the wily senator from Nevada? As it turns out, his tipster was Jon Huntsman Sr., the father of one of Romney's opponents for the GOP nomination, according to the book.

The younger Huntsman, Obama's former ambassador to China, doesn't come off too well either. Despite reportedly insisting to the administration that he wouldn't run for president, he nevertheless met with consultants and strategists while still working for the White House. Turns out that back-stabbing runs in the family.