In the likely general election match-up between John McCain and Barack Obama, there are more than a few obvious differences - in both policy and, certainly, personality.

Perhaps the most obvious, however? Barack Obama is young. McCain, not so much. At 71 years old, John McCain is old enough to be his opponent’s father, although don’t plan on the two sitting down to dinner anytime soon.

McCain’s age presents an interesting paradox for the Arizona senator, in that it can alternately be conveyed as both an asset and a liability. The McCain campaign has argued - to varying degrees of success - that its candidate’s age is telling of experience, and there can be no disagreement that he has much of that.

The Obama campaign, by contrast, has largely (and probably wisely) left speculation over McCain’s age to the Democratic rumor mill and blogosphere. Here, the conversation has generally focused on the potential health risks of electing a 72-year-old with a history of cancer to the most important office in the United States, perhaps the world. A seemingly clean bill of health made public by the McCain campaign weeks ago has quieted some of the criticism, but the issue remains touchy.

That issue, however, will only intensify so long as McCain continues to make the kind of what-was-he-thinking verbal/mental gaffes of the kind he most recently made last week, when he claimed that U.S. troops were “drawn down to pre-surge levels.”

The problem is, that’s not true. In fact, it’s off by tens of thousands.

What’s even more troubling than McCain’s consistent misinformation on one of his signature issues, is that he refuses to admit he’s made a mistake. In fact, following the recent remark, McCain reaffirmed his remarks when questioned, and said they represented “just facts.”

So much for the Straight Talk Express.

Several weeks ago, McCain drew similar criticism when, for the second time, he failed to correctly differentiate between Shiite and Sunni factions in Iraq. And in October of last year, McCain stated in a GOP presidential debate that “the first thing I would do is make sure we have a missile defense system in place in Czechoslovakia and Poland,” despite the fact that Czechoslovakia was split in two in 1993 and no longer exists.

The outrageousness of the remarks are disturbing enough, but McCain’s insistence that Barack Obama is “naive” on matters of Iraq and Iran is ludicrous. Obama may not have the experience of McCain, but it’s the elder statesman who seems sorely lacking in reality.

With all due respect to the Arizona senator, the old man’s losing it, and if the Straight Talk Express doesn’t get a much-needed tune-up, he will lose it all in November.