GOP presidential candidate Ben Carson is not ruling out having Donald Trump as his running mate in 2016.

Carson said Friday that he would be open to joining a White House ticket with the outspoken billionaire.

“All things are possible, absolutely,” he told host Neil Cavuto on Fox News’s “Your World with Neil Cavuto.”

{mosads}“I have had a chance to associate with him now that I have moved down to Florida,” Carson said of Trump.

“He’s a very smart guy,” he added. “And he is a fun guy. So, I will leave it at that.”

Carson also said he does not believe Trump should back down from his criticism of illegal immigrants and America’s border security.

“I would say that there’s a whole lot of oxygen in the room, and we need to hear everybody,” he said. “We need to discuss these things openly.”

“I like people who are willing to say what they believe.”

“I have learned how to tone it down a little bit, so that people can actually hear what I’m saying, and not just focus on the words, but that’s a skill people learn with the course of time,” he added.

The retired neurosurgeon criticized political correctness, arguing it is hurting the country.

“There’s no question that we are in the process in this country of giving away all of our values and principles for the sake of political correctness,” Carson said.

“And as a result of that, we’re in a tailspin.”

Trump has weathered heavy criticism since launching his presidential bid three weeks ago.

In the speech announcing his candidacy, he targeted Hispanic immigrants and Mexico.

“They’re sending people who have a lot of problems,” Trump said at New York’s Trump Tower. “They’re bringing drugs. They’re bringing crime. They’re rapists,” he added. “And some, I assume, are good people.”

While those remarks have stirred a backlash against Trump and his businesses, it has also coincided with a rise in the polls for the real estate mogul. A new survey released Thursday showed him leading the entire GOP field, and he is polling strongly in New Hampshire and North Carolina.

Carson said Friday that Trump had helped voters recognize the flaws in municipal “sanctuary” laws for illegal immigrants, which have been blamed for the release of the suspect in a recent San Francisco slaying.

Trump has repeatedly attacked cities for not cooperating with federal authorities on deportations.

“I certainly don’t think there’s any rational reason for sanctuary cities,” Carson said.

“I’m glad there’s focus on them now, because I would like the people who advocate for them to come out and tell why we need them,” he added. “And I can tell them 100 reasons why we don’t.”