Top Obama Adviser Likens Romney to Nixon on ABC News (Audio)

President Obama's senior campaign strategist had harsh words for Mitt Romney, the leading contender for the Republican presidential nomination, in a recent interview with ABC News.

our editor recommends

Gwen Stefani to Host Fundraiser with Michelle Obama

George Clooney to Appear at Mega-Dollar Obama Fundraisers in Geneva

Oliver Stone Says Obama 'Hasn't Kept' His Promises, Calls Mitt Romney an 'Idiot'

VIDEO: Donald Trump Slams Cher Over Anti-Romney Comments, Calls Her a 'Loser'

Related Topics

•Politics

He's "the most secretive candidate that we've seen, frankly, since Richard Nixon," David Axelrod told ABC News Radio White House correspondent Ann Compton on the first stop on Obama's campaign bus tour through Ohio.

PHOTOS: 20 Biggest Political Players in Hollywood

He “won’t release his tax returns, won’t reveal his bundlers, left Massachusetts with the hard drives from his computer," Axelrod said. "He believes in keeping the public in the dark."

Romney released his 2010 tax return but has declined to make public any of his other returns.

Axelrod said he isn't accusing Romney of cheating on his taxes, but he said that Romney's Bermuda-based company, Sankaty High Yield Asset Investors Ltd., Cayman Islands funds and Swiss bank account raise questions.

STORY: Brad Pitt's Mother Pens Anti-Gay, Anti-Obama Letter to Local Newspaper

"The only reason to have these accounts is to shelter your taxes," he said. "The question is, exactly what did he pay, and I think that he -- there's only one way to answer that question. If you don't have anything to hide, why not just release that information? And Gov. Romney really doesn’t have a good answer for that."

Romney's reps didn't respond to a request for comment from ABC News, but his camp recently called attacks on him related to his foreign assets -- by likes of Vanity Fair and others -- "false and ridiculous."

Romney has been slammed by some in Hollywood recently, including Oliver Stone, who called Romney an "idiot" in a THR cover story; Joan Rivers, who called both Romney and Obama "idiots," and Bruce Willis, who called the GOP politician "a disappointment, an embarrassment."

STORY: Morgan Freeman: Obama Not 'First Black President'

Romney's five sons recently appeared on TBS' Conan, where they revealed that he loves to watch Saturday Night Live, to sing and to play prinks, among other tidbits.

Listen to the ABC News inteview below.