Leave it to Karl Rove to call a spade a spade and expose Joe Biden for the truth challenged liberal he is.

Biden is not only a liar, he is a serial liar incapable of being truthful about almost anything. He is also a plagiarizer, a backstabber, and just a plain old gossiply blabbermouth.

This current brouhaha erupted over a Biden brag about going into the Oval Office and lecturing President Bush about leadership:

Karl Rove called Joe Biden a "blowhard" and a "liar" in response to some of the vice president's comments about the Bush administration.

"He's a serial exaggerator. If I was being unkind I would say he's a liar, but it's a habit he ought to drop," Rove said on FOX News. ""You should not exaggerate and lie like this when you are the Vice President of the United States."

Rove's comments are the harshest and most pointed yet in an ongoing feud between Biden and Bush administration officials, including Vice President Dick Cheney.

The former Bush advisor was referring to Biden's comments earlier this week on CNN that he and President Bush once had an exchange in the Oval Office, where Bush said, "'Well, Joe ... I'm a leader," and Biden responded: "Mr. President, turn and around look behind you. No one is following."

"It didn't happen," Rove said. "It's his imagination. It's a made-up, fictional world. He ought to get out of it and get back to reality."

Rove, who called Biden a "blowhard," also took aim with Biden's previous remarks that he had 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."