Donald Trump defended his treatment of women and the tenor of his campaign on Monday in a radio interview with a conservative committed to derailing his White House bid.

Milwaukee radio host Charlie Sykes pushed Trump about his increasingly personal jabs at Ted Cruz and his wife, Heidi Cruz, before revealing to the GOP front-runner that he is a “#NeverTrump guy” – a movement aimed at preventing Trump for becoming the Republican nominee.

“I didn’t know that, but I assume you’re also an intelligent guy. I know you’re an intelligent guy, and you understand what’s going on,” Trump said.

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In the 17-minute interview, Trump placed the blame for the increasingly nasty tone of the GOP primary on Cruz and said the Texas senator should apologize to him for an anti-Trump group’s digital ad featuring a provocative photo of Trump’s model wife.

Trump in turn threatened to “spill the beans” on Cruz’s wife and retweeted an unflattering photo of her.

“I didn’t start it, he started it. Again, if he didn’t start it, nothing like this would have happened,” Trump told Sykes, adding that Cruz owes him an apology.

“I expect that from a 12-year-old bully on the playground. Not somebody who wants the office held by Abraham Lincoln,” Sykes told Trump.

Trump called his actions a “minor response” to the group’s ad and said he has “been better to women than any of these candidates, frankly.”

And though he agreed that wives and children should be kept out of the campaign, Trump declined to admit fault or apologize to Heidi Cruz.

“I don’t know Ted Cruz’s wife, I’m sure she’s excellent,” Trump said. “I just don’t know her.”

This article first appeared on NBCNews.com.