Republican strategist Karl Rove called Vice President Biden a "liar" on Thursday, dramatically escalating a feud between Biden and aides to former President George W. Bush over Biden's claims to have rebuked Bush in private meetings.
"I hate to say this, but he's a serial exaggerator," Rove told FOX News. "If I was being unkind I would say liar. But it is a habit he ought to drop."
Rove added: "You should not exaggerate and lie like this when you are the Vice President of the United States."
Biden's office did not immediately respond to a request for comment, although Biden spokesman Jay Carney told Fox on Wednesday: "The vice president stands by his remarks."
Carney was referring to two controversial assertions by Biden, the latest coming Tuesday during an interview on CNN.
"I remember President Bush saying to me one time in the Oval Office," Biden began, "'Well, Joe,' he said, 'I'm a leader.' And I said: 'Mr. President, turn and around look behind you. No one is following.'"
The exchange is purely "fictional," said Rove, who was Bush's top political adviser in the White House.
"It didn't happen," Rove, a FOX News contributor and former Bush adviser, told Megyn Kelly in an interview taped for "On The Record." "It's his imagination; it's a made-up, fictional world.
"He ought to get out of it and get back to reality," Rove added. "He's making this up out of whole cloth."
Rove also said few presidents would spend a long time with anybody in the Oval Office, particularly "with all due respect, a blowhard like Joe Biden."
Rove's skepticism was echoed by a variety of other Bush aides, including former White House press secretary Ari Fleischer, chief of staff Andy Card and legislative liaison Candida Wolff.
They also disputed a similar assertion made by Biden in 2004, when the former senator from Delaware told scores of Democratic colleagues at a lunch that he had challenged Bush's moral certitude about the Iraq war during a private meeting in the Oval Office. Two years later, Biden repeated his story about dressing down the president.
"When I speak to the president - and I have had plenty of opportunity to be with the president, at least prior to the last election, a lot of hours alone with him. I mean, meaning me and his staff," Biden said on HBO's "Real Time with Bill Maher" in April2006. "And the president will say things to me, and I'll literally turn to the president, say: 'Mr. President, how can you say that, knowing you don't know the facts?' And he'll look at me and he'll say - my word - he'll look at me and he'll say: 'My instincts.' He said: 'I have good instincts.' I said: 'Mr. President, your instincts aren't good enough.'"
On Thursday, Rove ridiculed the claim that Biden spent "a lot of hours alone with" Bush.
"Joe Biden was never alone with the president for more than few moments," Rove said. "There was staff in the room the whole time."
Rove was equally appalled by Biden's claims of having given Bush his comeuppance.
"If you notice, all of these incidents have the same structure: Joe Biden courageously raises the impudent question; the president befuddles the answer; and Joe Biden drives home the dramatic response."
Rove scoffed at Biden's claims that "he and the president were sitting there in the Oval Office, he was tutoring the president, he was asking him the critical questions that no one was willing to confront him with."
"With all due respect to the vice president, these are the kind of things you can get away with if you are a United States Senator, ora backbencher in the U.S. House of Representatives," Rove said. "You should not exaggerate and lie like this when you are the Vice President of the United States."
Carney declined to specify the dates of his boss's purported Oval Office scoldings of Bush. Nor would he provide witnesses or notes to corroborate the episodes.
Throughout his career, Biden has often been accused of boasting about his accomplishments, embellishing his credentials and even stealing the words of others. He dropped out of the 1988 presidential race after being accused of plagiarizing British Labor Party leader Neil Kinnock.
Last July, Biden came under fire for telling a questionable story about being "shot at" in Iraq. When questioned by the Hill newspaper, Biden backpedaled by saying: "I was near where a shot landed."
Biden went on to say that some sort of projectile "landed" outside a building in the Green Zone where he and another senator had spent the night during a visit in December 2005. The lawmakers were shaving in the morning when they felt the building shake, Biden said.
"No one got up and ran from the room-it wasn't that kind of thing," he told the Hill. "It's not like I had someone holding a gun to my head."
In September, Biden again raised eyebrows with another story about his exploits in war zones -- this time on "the superhighway of terror between Pakistan and Afghanistan, where my helicopter was forced down."
"If you want to know where Al Qaeda lives, you want to know where bin Laden is, come back to Afghanistan with me," Biden bragged to the National Guard Association. "Come back to the area where my helicopter was forced down, with a three-star general and three senators at10,500 feet in the middle of those mountains. I can tell you where they are."
But it turns out that inclement weather, not terrorists, prompted the chopper to land in an open field during Biden's visit to Afghanistan in February 2008. Fighter jets kept watch overhead while a convoy of security vehicles was dispatched to retrieve Biden and fellow Sens. Chuck Hagel and John Kerry.
"We were going to send Biden out to fight the Taliban with snowballs, but we didn't have to," joked Kerry, a Democrat, to the AP. "Other than getting a little cold, it was fine."
Bill Sammon is FOX News Channel's (FNC) vice president of News and Washington managing editor.