Aides to former President George W. Bush are challenging the veracity of Vice President Joe Biden's claim this week of having privately castigated Bush, who does not remember the incident or an earlier episode in which Biden claims to have similarly rebuked Bush.
Biden spokesman Jay 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.
"The vice president stands by his remarks," Carney told FOX News without elaboration.
Those remarks include a shot that Biden took at Bush on Tuesday.
"I remember President Bush saying to me one time in the Oval Office," Biden told CNN, "'Well, Joe,' he said, 'I'm a leader.' And I said: 'Mr. President, turn and around look behind you. No one is following.'"
That exchange never took place, according to numerous Bush aides who also dispute a similar assertion by Biden in 2004, when the former senator from Delaware told scores of Democratic colleagues 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 April 2006. "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.'"
Bush aides now dispute the veracity of both assertions by Biden.
"I never recall Biden saying any of that," former White House press secretary Ari Fleischer said after reviewing detailed notes of Bush's White House meetings with Biden, which include numerous direct quotes from Biden. "I find it odd that he said he met with him alone all the time. I don't think that's true."
Fleischer said that whenever Bush met with Sen. Biden, the meeting also included a congressional counterpart so as to not "antagonize" the House.
Karl Rove, former White House political adviser, also was skeptical of Biden's claim to have spent "a lot of hours alone" with Bush.
"I remember checking on such a Biden exaggeration while at the White House and no one witnessed the meeting and his comments in remotely the same way," Rove said.
Candida P. Wolff, Bush's White House liaison to Capitol Hill, said the only meetings she remembered between Bush and Biden also included other lawmakers. She said such meetings were held in the Cabinet Room or the Eisenhower Executive Office Building, not the Oval Office, and certainly did not last for "hours."
"The president would never sit through two hours of Joe Biden," Wolff said. "I don't ever remember Biden being in the Oval. He was such a blowhard on all that stuff - there wasn't a reason to bring him in."
Andy Card, former White House chief of staff, reviewed the two Biden claims and said: "This does not ring true to me. I doubt that it happened."
A spokesman for Bush declined comment, although a person close to the former president said Bush does not remember either episode.
This is not the first time the veracity of Biden's assertions has been challenged. In 1988, he dropped out of the presidential race after being accused of plagiarizing British Labor Party leader Neil Kinnock. The Washington Post also cited "the senator's boastful exaggerations of his academic record."
Last year, liberal Slate magazine recalled that "Biden's misdeeds encompassed numerous self-aggrandizing thefts, misstatements, and exaggerations that seemed to point to a serious character defect."
Also last year, Biden came under fire for telling a questionable story about being "shot at" in Iraq.
"Let's start telling the truth," Biden said during a presidential primary debate sponsored by YouTube in July. "Number one, you take all the troops out -- you better have helicopters ready to take those 3,000 civilians inside the Green Zone, where I have been seven times and shot at. You better make sure you have protection for them, or let them die."
But when questioned about the episode afterward by the Hill newspaper, Biden backpedaled from his claim of being "shot at" and instead allowed: "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."
Seven weeks after claiming to have been "shot at" in Iraq, 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 at 10,500 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.