Republicans know they’re in for trouble when the first two words of an AP profile of their candidate for president are “Temper, temper.”

John McCain’s temper is legendary. Now, as McCain assumes the mantle of the head of the GOP, it’s becoming common knowledge.

The New York Times also examined the notorious McCain temper this weekend:

One of the trademarks of Mr. McCain’s rebel image has been his inability to cloak his emotions, especially anger. He has been prone to volcanic blowups over the years. And while he would hardly be the first president with a temper, Mr. McCain has been ever vigilant of late about resisting provocation.

Can he be vigilant til election day?

Back in 1964, the Republicans said of their candidate, Barry Goldwater, “In your heart, you know he’s right.” The Democrat’s response was “In your guts, you know he’s nuts.”

The 2008 version of that statement for Republicans (a little more politically correct) is that in their hearts, they think McCain’s wrong. And, in their guts and in their own experiences, Republicans know McCain is, let’s say, volatile and unstable.

Matt Yglesias nails why this matters. It’s not just about screaming obscenities at other Senators, which, as Yglesias notes is “a faux pas that can be overcome with an apology after the fact.” But, here’s the real issue with McCain’s temper:

Those same instincts could, however, be a major problem if applied to the DMZ in Korea or the Taiwan Straits.

Or any other hot spot around the world.