"My argument is this is a racketeering case that went on for 30 years," Giuliani told host Martha MacCallum.

Giuliani, the president's personal attorney, has come into possession of a hard drive containing the messages, which formed the centerpiece of the New York Post's report Wednesday that Hunter Biden introduced his father, then-vice president Joe Biden, to an executive at Burisma Holdings -- the Ukrainian energy firm where Hunter Biden sat on the board. Joe Biden, now the Democratic presidential nominee, has repeatedly denied discussing Hunter's overseas business interests with him. 

The former mayor, now President Trump's personal attorney, told MacCallum that both he and the Post separately may only have gotten through one-third of the information stored on the hard drive.