(I debated between IMHO and GQ, but I figure answers are going to be speculative, so I opted for the former.)
Back when Giuliani was running for president, I started wondering what other presidents had been former mayors.
There aren’t many. Coolidge was the last president who had been a mayor (Northampton, MA) – though of course he’d served as Lieutenant Governor and Governor of Massachusetts after that and before being elected president.
John Lindsay, also a NYC mayor, ran for president in '72. Very unsuccessfully.
It’s conventional wisdom these days that governors fare better than senators in presidential contests because of their executive experience. I get why not many mayors can leap straight to a viable presidential candidacy – I can’t imagine many cities other than New York or maybe LA could claim a viable level of experience – but why aren’t more former mayors with subsequent higher-level experience running for president? Do they not run for (or achieve) governorships in high numbers? Do most mayors not run for higher offices than that? What’s up?