The pair corresponded frequently when Giuliani was New York City's mayor, and Trump was just a celebrity real estate developer, and Giuliani biographer Andrew Kirtzman told The Daily Beast podcast "The New Abnormal" that he reviewed a lot of those exchanges while writing Giuliani: The Rise and Tragic Fall of America's Mayor.
“We found a lot of correspondences between Giuliani and Trump during [Giuliani’s] mayoralty, and it was just fascinating," Kirtzman said. "I mean, there was this kind of need that they both seemed to feel to impress the other, and I think that that still exists to this day."
Giuliani wanted to head the State Department, but a cursory background check scuttled those plans.
“He started just hearing all of these negative stories about him, about his drinking -- Giuliani waged this campaign in the press to get the job which turned Trump off," Kirtzman said. "They launched an investigation internally in the campaign into Giuliani’s clients, and he had so many clients with potential conflicts that had filled a report, dozens of pages, and eventually, Trump moved on."
Giuliani and his third wife, Judith, stayed at Mar-A-Lago after the former mayor lost his bid for the Republican Party presidential nomination in 2008.“For the next month, Trump houses them at this kind of beachfront property, and [they] found there were tunnels under Mar-a-Lago, where they were able to kind of walk back and forth undiscovered," Kirtzman said. "It was there that Giuliani kind of was allowed to get back on his feet and rejoin the world."