The combative former mayor of New York has shown he is resolute in a crisis but also creates turmoil himself.

In three campaigns for mayor of New York, Rudy Giuliani lost a squeaker, won a squeaker and won by a landslide. What's more, he did it as a Republican in a city where Democratic voters have a 5-to-1 majority. Now, he's in a position that no New York mayor has ever been in: national front-runner for the Republican presidential nomination.