The back-and-forth verbal jabs between former Bush White House deputy chief of staff Karl Rove, his deputies at American Crossroads and some of the conservative movement’s so-called “critically important figures” took another intense turn on Mark Levin’s radio show on Thursday, with Iowa Republican Rep. Steve King entering the fray.

“[L]et me put something to you folks about Karl Rove — what a propagandist this man is,” Levin said at the end of his program. “He keeps bringing up Christine O’Donnell. Karl Rove has lost more races that he’s been involved in than Christine O’Donnell. She has lost one. Rove has lost scores. And as soon as she was nominated, he went on TV on the ‘Hannity’ show and started smearing her.” (RELATED: Conservative leaders write angry letter after staffer dares mock their “beloved” Brent Bozell”)

“And he put out emails to all the pseudo-conservatives inside the beltway trashing her. He wanted her defeated,” Levin continued. “He wanted Mike Castle to win — Mike Castle, anti-conservative, pro-abortion, pro-big spending, on and on and on. He’s also up there with that stupid little third-grade whiteboard of his, with his fourth-grade writing style, talking about how they committed $30 million to tea party candidates. Ladies and gentlemen, we’ve had to fight through these primaries to get the tea party conservatives nominated. And then his group has put money into the race.”

Levin, the author of “Ameritopia: The Unmaking of America,” urged American Crossroads’ donor to put their money elsewhere in the future if they are indeed interested in promoting conservative candidates.

“Karl Rove, let me tell you something — you’re despised by the grassroots,” he said. “And let me tell your donors something — stop wasting your money. There are organizations all over this country that need your help, who are organizing at the grassroots level, who aren’t making money. And these people will work harder and do better in terms of nominating candidates to help save this country.”

One of the individuals Levin put his support behind was King, whom Rove’s group targeted for not being truly “conservative.”

“Well, the first thing I thought was the elitist attitude — the idea you can wake up with the checkbook of mostly somebody else’s money and decide in any state who would be the nominee for the United States Senate — that is an arrogant attitude,” King told Levin.

Levin urged King to use Rove as a foil against any opponent he may have in upcoming races.

“Let me tell you something, Steve King and all you conservatives out there who are thinking about running in these primaries and so forth — your best commercial is going to be that your opponent is funded by Karl Rove. I’m serious, Steve King — I think Karl Rove’s name, I think his organization are poison in conservative and Republican circles in many respects.”

At the very close of his program, Levin challenged Rove to give it his best shot.

“Bring it on, Karl baby,” Levin added. “Bring it on, doughboy. Bring on your little whiteboard. We’re ready.”

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