Is McCain Lying, Stupid or Both?

One day after Joe Lieberman corrected him in public for once again stating his oft-repeated false claim that Iran, a majority Shiite country, was supplying the mostly Sunni militant group, al-Qaeda, McCain unbelievably repeated the false claim again:

For the third time in two days, the Arizona Republican has pushed the definitively false statement that the terrorist group Al-Qaeda was getting assistance from Iran, even though he was publicly ridiculed for the same false assertion on Tuesday.

This time, in a statement from his campaign honoring the fifth year anniversary of the war, McCain wrote:

"Today in Iraq, America and our allies stand on the precipice of winning a major victory against radical Islamic extremism. The security gains over the past year have been dramatic and undeniable. Al Qaeda and Shia extremists -- with support from external powers such as Iran -- are on the run but not defeated."

On Tuesday, the senator, appearing in Israel, made a nearly identical assertion that al-Qaeda was leaving Iraq to retool and regroup in Iran.

[...]

Sen. Joseph Lieberman, who was accompanying McCain on the trip, was forced to lean over and whisper in McCain's ear that it was Shiite extremists, not Sunni al-Qaeda, that was going to predominantly Shiite Iran.

So he's still repeating a spiel he knows -- and has been told, in public yet -- is wrong.

There are three possible explanations: