He also claimed that recently revealed text messages by Trump-era officials regarding Ukraine paint a different picture than what Rep. Adam Schiff, D-Calif., and Democrats seeking an impeachment inquiry are claiming.
"It doesn't say, 'President Trump wants you to interfere in the 2020 election.'" he said.
"It says, 'President Trump wants you to investigate substantial allegations of federal crimes partially committed in Ukraine by high-level American officials' -- exactly what an honest president should do, and exactly what Obama didn't do five years ago that could've stopped the whole thing."
Giuliani -- Trump's personal attorney -- underlined his work as a prosecutor in New York, where he pursued cases against mobsters and corrupt politicos, suggesting he "has a nose for corruption."
"The big question that has to be asked is, in 2015 when The New York Times first exposed the enormous conflict that [Joe] Biden had in Ukraine and criticized him -- how could you have your son taking money from a corrupt oligarch? Why didn't Obama stop it? Any honest president would've stopped it."
At the time, Hunter Biden served on the board of a Ukrainian natural gas company called Burisma Holdings.
Giuliani added he believed that a more subjectively responsible investigation into the Bidens and Ukraine will reveal the Obama White House to be marked with infamy in the history books.
"Is it possible if we break this open we're going to find out the Obama administration might be one of the more corrupt administrations in a very long time?" he asked.
"Is it possible that Democrats would cover that up and fight for their lives and have Schiff going out violating laws in order to frame the president of the United States?"
In that regard, Giuliani claimed powerful attorneys are considering whether to sue individuals like the California Democrat.
"Not a joke, not a threat ... and, thank you, Schiff, because you keep lying every day," Giuliani remarked.