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Following the action-packed Fox News debate at Detroit's Fox Theatre, Bill O'Reilly spoke to the "Final Four" Republican presidential candidates about how they thought the night went and what they make of the 2016 race.

O'Reilly asked front-runner Donald Trump about the moment in the debate when he stated that he would honor his pledge to support the eventual GOP nominee - no matter who it is - and not launch a third-party run.

"The Republican Party has been pretty nice to me," Trump said, adding that he has brought millions of people into the party, as well.

"The best chance of winning is me to run as a Republican. I will beat Hillary Clinton."

O'Reilly asked Rubio about the upcoming Florida primary - which is just around the corner on March 15 - and how he plans to narrow the 20-point gap between he and Trump.

Rubio said he doesn't believe the number is actually that large, but he acknowledged he's an underdog and it will be a tough race.

He said, however, that he knows the people of Florida and he's confident that he will emerge victorious in The Sunshine State.

"In Florida, in particular, what you have are people who are coming to get away from something else," Rubio said. "There's a real understanding in Florida of how important and unique America is, but how easy it is to lose something like that with the wrong leadership."

O'Reilly pressed Cruz on if he believes Trump is an "honest man" or not.

Cruz said that Trump believes everything he says, but the billionaire could also say two opposite things in the course of one conversation and pass a lie detector test.

But you don't think he's dishonest? O'Reilly pressed.

"I'm not going to speak to his heart. His heart is between him and God," Cruz said. "I can tell you his rhetoric doesn't match up with his record."

O'Reilly also challenged Kasich in his post-debate sit-down with the Ohio governor.

The "Factor" host acknowledged that Kasich has the best policies of any candidate, but he doesn't have the fire of the others.

"You're not feeling the anger, and that is what has held you back, in my opinion," O'Reilly said.

"I'm not going to come out here and scream and yell," Kasich said. "It's not what's lifting me."

He said he's going to win by being "the adult in the room."

Watch the "Factor" interviews above.

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