Not since Teddy Roosevelt took on Tammany Hall a century ago has a New York politician closely linked to urban reform looked like presidential timber. But today ex–New York mayor Rudy Giuliani sits at or near the top of virtually every poll of potential 2008 presidential candidates. Already, Giuliani’s popularity has set off a “stop Rudy” movement among cultural conservatives, who object to his three marriages and his support for abortion rights, gay unions, and curbs on gun ownership. Some social conservatives even dismiss his achievement in reviving New York before 9/11. An August story on the website Right Wing...