President Obama’s political advisers secretly explored the possibility of replacing Vice President Biden on the 2012 ticket with then-Secretary of State Hillary Rodham Clinton to capi­tal­ize on her popularity when Obama’s reelection seemed precarious, according to a new book.

In late 2011, a team of Obama’s campaign strategists conducted polling and convened focus groups to explore the political potency of installing Clinton as his running mate, according to “Double Down,” a book about the campaign by journalists Mark Halperin and John Heilemann.

William M. Daley, the White House chief of staff at the time, was the most forceful advocate of exploring the switch, which the authors write was studied by “the top echelon of Obamaworld” and kept secret from the vice president. But the team concluded that adding Clinton “wouldn’t materially improve” Obama’s chances of winning a second term.

Obama adviser David Plouffe, who the book says was part of the small group, tweeted Thursday that the idea of swapping in Clinton was “not even entertained.”

The new account paints the clearest portrait yet of the lengths to which Obama’s advisers went to explore replacing Biden, a move that had been rumored but never spelled out in detail. The book, billed as a sequel to “Game Change,” Halperin and Heilemann’s account of the 2008 election, goes on sale Tuesday.

The book’s revelations were first reported Thursday evening by the New York Times. The Washington Post independently obtained a copy.

The book is a narrative reconstruction of the behind-the-scenes machinations of the campaigns of Obama and Republican nominee Mitt Romney. It details Romney’s search for a vice-presidential nominee. “Project Goldfish,” as his vetting team called its operation, was so secretive that researchers referred to the five finalists by aquatic names — New Jersey Gov. Chris Christie (Pufferfish), former Minnesota governor Tim Pawlenty (Lakefish), Sen. Rob Portman of Ohio (Filet-O-Fish), Sen. Marco Rubio of Florida (Pescado) and Rep. Paul Ryan of Wisconsin (Fishconsin).

Romney initially crossed Christie off his short list. The governor’s vetting file was incomplete, and Romney had been bothered by Christie’s propensity to show up late at campaign events and by his lack of physical fitness, the book says.

“Romney marveled at Christie’s girth, his difficulties in making his way down the narrow aisle of the campaign bus,” the authors write. “Watching a video of Christie without his suit jacket on, Romney cackled to his aides, ‘Guys! Look at that!’”

But Romney reconsidered Christie at the strenuous urging of two top campaign strategists, Stuart Stevens and Russ Schriefer. An 11-day crash vetting left unknowns, however.

According to a memo published in the book, the unanswered questions included those about a defamation lawsuit from earlier in Christie’s career; a Securities and Exchange Commission settlement involving Christie’s brother, Todd; the names and documented status of Christie’s household employees; his clients from his time as a securities industry lobbyist; and his medical history.

Beth Myers, who led Romney’s vice presidential search, said in a statement Thursday that “Governor Christie complied fully with the Romney campaign’s request for documents in a timely manner, including a complete medical report from his internist and cardiologist.”

The book describes Christie as concluding that Romney’s campaign team was “a gaggle of clowns who couldn’t organize a one-ring circus.” After Christie drew media criticism for his keynote address at the Republican National Convention, he confronted Romney adviser Ron Kaufman in the arena concourse and berated him with expletives.

“I’m tired of you people!!!” the book quotes Christie as saying. “Leave me the [expletive] alone!!!!”

The book also sheds new light on flash points in the campaign, including Senate Majority Leader Harry M. Reid’s claim that Romney had not paid taxes for 10 years. Publicly, Reid (D-Nev.) had cited a confidential source, but he identified the source to Obama’s inner circle as Jon Huntsman Sr., the father of former Utah governor Jon Huntsman Jr., a Romney primary opponent. Last year, Huntsman Sr. denied that he was Reid’s source.

Even as he was labeled a liar by Romney’s surrogates, Reid refused to back down from his claim. The book explains why he might not have been inclined to dial it down: A pair of top Obama aides “were over the moon” at Reid’s tactic, and Obama expressed no disapproval.

When Romney held a news conference to criticize the administration’s handling of the deadly attacks on a U.S. diplomatic post in Benghazi, Libya, Biden’s reaction was: “He’s a horse’s ass.” And later, when press secretary Jay Carney briefed Obama on Romney’s attempts to score political points from the attacks, the president said, “It’s practically disqualifying.”

The book details Romney’s efforts to revive his campaign following revelations that he had dismissed “47 percent” of Americans at a private fundraiser. Meg Whitman, a Romney friend and former eBay chief executive, and Portman convened a “war council” at the Boston headquarters for Romney to hear advice from people outside his bubble.

The war councilors included Sen. Kelly Ayotte (N.H.) and South Carolina Gov. Nikki Haley as well as Virginia Gov. Robert F. McDonnell, whose appraisal was particularly harsh: “For some reason, people don’t like you.”