All that said, a similarity to President Bush won't be an asset in a general election. Bush was ill-served by his excessive loyalty to a tight, hermetically sealed group of advisers, and didn't take criticism well. Giuliani has the same tendencies. He gives the impression of being even less interested in diplomacy than the Bush of the first term. The change voters are looking for probably isn't "Bush -- except even more bellicose and disdainful of political opponents."
Giuliani still has major ideological -- and personal -- vulnerabilities. The question is whether the liberal aspects of his record as mayor, together with his spectacularly rocky personal life, will overwhelm his instinctual appeal to Republican voters. We won't know until we see how he fares under what probably will be a barrage of negative ads in the stretch-run of the nomination fight.
He likes to say that a winning Republican coalition consists of economic conservatives and national-security hawks -- pointedly excluding social conservatives. As a factual matter, this is wrong; Republicans can't win national elections without appealing to social-conservative voters who might not buy their free-market economics. As a tactical matter, it's foolish; he should continue to minimize his differences with social conservatives rather than implicitly read them out of the GOP coalition.
Giuliani's best selling point in the primaries is that -- whatever his media coverage says -- he's not something new under the sun. He's an archetype that Republican voters know and love -- the gun-slinging sheriff, just with a different ZIP code.