When it comes to personal temperament, Governor Romney would rate the highest for his even keel, regardless of what events are swirling around him, with Rudolph Giuliani a close second.
Temperament is far more important for a President than for a candidate. A President has to be on an even keel 24/7, for four long years, despite crises that can break out anywhere in the world at any time.
John McCain trails the pack in the temperament department, with his volatile, arrogant, and abrasive know-it-all attitude. His track record in the Senate is full of the betrayals of Republican supporters that have been the party's biggest failing over the years and its Achilles heel politically.
The elder President Bush's betrayal of his "no new taxes" pledge was the classic example, but the current President Bush's attempt to get amnesty for illegal aliens, with Senator McCain's help, was more of the same.
President Ford's pardon of Richard Nixon probably cost him the 1976 election and cost the country the disastrous Carter years.
McCain's betrayals include not only the amnesty bill but also the McCain-Feingold bill that violated the First Amendment for the illusion of "taking money out of politics." His back-door deal with Democrats on judicial nominations also pulled the rug out from under his party leaders in the Senate.
The White House is not the place for a loose cannon.
Contrast: David Cameron Suspends Vacation Over Foley Killing; Obama Heads Back To Vineyard | Christine Rousselle