Donald Trump. REUTERS/Brian Snyder Real-estate tycoon Donald Trump repeatedly blasted Glenn Beck on Saturday after the prominent conservative radio host accused him of voting for President Barack Obama in 2008.

"This really dopey guy ... this dopey guy, Glenn Beck, he looks like hell. No, he's like a dope. And I've watched him cry on television all the time. He's doing very badly. His thing is falling apart. His company is falling apart," Trump said at a campaign event in Portsmouth, New Hampshire.

The Republican presidential front-runner said he was quite "bothered" by Beck's Friday-evening interview with Fox News host Bill O'Reilly. During that interview, Beck repeatedly attacked Trump as a "progressive" and compared him to Obama.

"He voted for Obama in '08, come on Bill," Beck said as O'Reilly pushed back on his criticism of Trump.

Trump countered that claim the next day by touting his work on behalf of Obama's 2008 opponent: Sen. John McCain (R-Arizona).

"The guy goes on television last night with O'Reilly," the businessman recalled. "He says that I voted for Barack Obama. And I'm on John McCain's committee, raised a tremendous amount of money for John McCain, had dinner with John McCain and his wife right before the election, and I've got to listen to this idiot named Glenn Beck."

Trump also said he called O'Reilly and asked, "Bill why do you have a guy like that on television?"

"He's a failed guy," the candidate added later.

Trump also lashed out at Beck last October after the conservative commentator called him a "bully." Trump responded by calling Beck "irrelevant" and a "nut job" who "always seems to be crying."