CNN host Jake Tapper blasted Donald Trump surrogate Rudy Giuliani on Sunday for defending accusations that Hillary Clinton had been unfaithful to her husband.

On CNN's State of the Union, Tapper began interview his with Giuliani by pressing the former New York City mayor about allegation that Trump paid no federal income taxes for a period of years.

"The reality is this is part of our tax code," Giuliani insisted. "The man's a genius. He knows how to operate the tax code for the benefit of the people he's serving."

"He could be sued because his obligation as a businessman is to make money for his enterprise," he added. "It would have been insane for him not to take advantage of it."

"He's the first major nominee since 1978 not to release his tax returns," Tapper pointed out. "If you are proud of that, that's great. But I don't think you should be."

After spending eight minutes arguing with Giuliani over Trump's taxes, Tapper turned to the campaign's attacks on Clinton's marriage.

"Donald Trump launched a wild and unsubstantiated attack against Hillary Clinton last night," Tapper said, referring to Trump's assertion that Clinton had not been "loyal to Bill... and why should she be."

"Is that normal, stable behavior for a presidential nominee?" Tapper deadpanned.

"After she called him a racist, a misogynist, a xenophobic -- I don't know -- schizophrenic and I don't know what else she called him," Giuliani ranted. "I think it's fair game."

"Just to make stuff up?" Tapper shot back. "Just to make stuff up? Wild accusations, Hillary Clinton is cheating on Bill? No proof of it whatsoever. Everything's fair game?"

Giuliani insisted that Trump's had made a "sarcastic remark" to point out that "Bill Clinton has quite a past and Hillary Clinton has done quite a job on attacking people who were victims of Bill Clinton."

"I mean, I just find it hard to believe that Mr. Trump would want to start leveling accusations about people's marriages," Tapper concluded.

"I think the accusations are about Hillary Clinton taking money from countries that kill women!" Giuliani exclaimed.

"The accusation was that Hillary Clinton was cheating on Bill!" Tapper said, raising his voice. "That's what the accusation was! It was an unhinged and wild accusation. I can understand why you can't defend it because it's indefensible!"

"Well, that's your opinion," Giuliani griped as Tapper ended the interview.