In a debate among the three Democratic presidential candidates, Obama and Clinton accused each other of lying. Undoubtedly, many of these accusations were accurate, on both sides. As we all remember, if a politician's mouth is moving s/he is lying.
As a voter who usually votes GOP, I enjoy watching Democrats beat up on each other. Whatever the loser says about the winner will be ammunition for whichever GOP candidate ends up being the nominee.
These folks didn't learn the Great Communicator's Eleventh Commandment: never speak ill of a member of your own party. Reagan understood there was no point in Republicans beating up on their own folks.