Former New York City Mayor Rudy Giuliani told Greta Van Susteren tonight that Donald Trump has a chance to make a big impact in the 2016 presidential campaign.

Giuliani explained that Trump is a quick learner and has rapidly gotten better as a candidate.

The former mayor agreed with Trump's assessment that the nuclear deal with Iran is a tragic mistake.

"If you were negotiating a deal with Donald - and I've seen him - he would have taken that piece of paper and thrown it in your face and said, 'Go to hell,'" Giuliani said.

"The odds that Trump is going to make a big contribution to this campaign are getting better and better," Giuliani said. "He's hitting the right issues."

Watch more from "On The Record" above.

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