Matthew Yglesias, after linking to Matt Welch's instant-classic April Reason cover story, links an anti-Rudy manifesto by New York "civic-republican" Jim Sleeper*.
The first serious problem is structural and political: A man who fought the inherent limits of his mayoral office as fanatically as Giuliani would construe presidential prerogatives so broadly he'd make George Bush's notions of "unitary" executive power seem soft.
Even in the 1980s, as an assistant attorney general in the Reagan Justice Department and U.S. Attorney in New York, Giuliani was imperious and overreaching, He made the troubled daughter of a state judge, Hortense Gabel, testify against her mother and former Miss America Bess Meyerson in a failed prosecution charging, among other things, that Meyerson had hired the judge's daughter to bribe help "expedite" a messy divorce case. The jury was so put off by Giuliani's tactics that it acquitted all concerned, as the Washington Post's Ruth Marcus recalled ten years later in assessing Special Prosecutor Kenneth Starr's subpoena of Monica Lewinsky's mother to testify against her daughter.
At least, as U.S. Attorney, Giuliani served at the pleasure of the President and had to defer to federal judges. Were he the President, U.S. Attorneys would serve at his pleasure—a dangerous arrangement in the wrong hands, we've learned—and he'd pick the judges to whom prosecutors defer.
As mayor, Giuliani fielded close aides like a fast and sometimes brutal hockey team, micro-managing and bludgeoning city agencies and even agencies that weren't his, like the Metropolitan Transportation Authority and Board of Education. They deserved it richly enough to make his bravado thrilling to many of us, but it wasn't very productive. And while this Savonarola disdained even would-be allies in other branches of government, he wasn't above cutting indefensible deals with crony contractors and pandering shamelessly to some Hispanics, orthodox Jews, and other favored constituencies.
Good stuff, and worrisome if you care about executive power and civil liberties. But this isn't the kind of criticism that will hurt Giuliani in a general election, is it? I can't readily name a politician who's suffered because he "got too tough," as long as what/whom he was lording it over is unpopular.
*errata: I originally referred to Sleeper as a neoconservative. He ain't.