For the last week or so, the Giuliani and Romney campaigns have been going at each other with gusto. The Romney people criticize Rudy's associations, particularly Bernard Kerik, while the Rudy people note Romney's campaign differs from his record of governance. One explanation for this sudden in-fighting is that the two sides now perceive the other as the main obstacle to their candidate's winning the nomination. Another is that the modern campaign's need for "rapid response" to any criticism escalates such back-and-forth spats by ensuring every salvo is instantly countered. Dan Balz of The Washington Post covered the fight yesterday, but Paul Mirengoff of Power Line picks the winner:

Given the plausibility of their competing attacks, the main beneficiary would seem to be John McCain, who sees his two key New Hampshire rivals tarred, and who probably wins points for declining to attack them with comparable gusto. Yet McCain too has parted company with conservatives on key issues. And to some, Mike Huckabee is not a legitimate conservative at all, given his tax-and-spend approach to governing Arkansas. All of this explains why many were so eager for Fred Thompson to enter the race. But Thompson, whose record in the Senate was largely indistinguishable from McCain's, has had limited success firing up conservatives since his entry.

In light of these competing impurities, many conservatives are likely to choose their man based less on specific issues and more on factors like perceived competence and leadership skill, personal qualities, and perhaps electability.

Read Paul's full post at the link preceding. No doubt he is correct, especially in New Hampshire, where voters tend to stay undecided until very late in the process. Iowans also tend to dislike negative campaigning - although so far, this battle has been mainly confined to competing emails to media types from campaign spokespeople, and stayed out of the advertising most voters see.

In Iowa, the caucus rules make appealing to the supporters of other candidates very important. In any precinct, those caucus-goers who can't gather enough support for their first choice then caucus in support of their second choice candidate. No campaign is helped by the reputation of negative campaigning there.

In the meantime, McCain has quietly but steadily regained most of his lost support in national polls, boosted by the success of the "surge" strategy in Iraq (which he had been advocating for some three years before it was adopted) and regular confirmations of his "electability" in poll match-ups with Hillary Clinton. The only way to win a fight like the one between Rudy and Romney is to stay the heck out of it.