Donald Trump opened fire on Bill O'Reilly Friday, saying if he were President, he wouldn't hire O'Reilly for Defense Secretary.

"I think you're starting to be too soft for Secretary of Defense," Trump said, starting the verbal volley.

Ooh, snap.

"Yeah, compared to you! Attila!" O'Reilly fired back, "I might be a moderating influence!"

Running with the reference, Trump said there might be less war if the notorious Hun was in charge. "They're going to respect Attila and they're not respecting what you have right now."

O'Reilly suggested perhaps Trump could work that into a campaign slogan, "'I'm not Attila, but I'm close'. How about that on a bumper sticker?"

Trump nixed that idea.

"You know what? I'm not Attila. I have a big heart. I'm going to take care of people and I'm going to make sure this country comes first."

The interview was the third and final part of a series of segments O'Reilly aired this week with the potential presidential candidate. Trump has said he will announce whether he will run for president, by June.