Romney, the apparent Republican presidential nominee, also took a swipe at President Obama, calling him a "big money Democrat" who is even more liberal than former President Clinton, the Omaha World-Herald reported.
The Romney campaign raised $800,000 at a fundraiser dinner at the Omaha Hilton, the report said.
Also Thursday, Romney apologized repeatedly for high school pranks that may have hurt other students. But in an interview with Fox News, the former Massachusetts governor said he doesn't remember them.
Romney spent his teenage years spent at Cranbrook, a prestigious prep school in Michigan, CBS News said.
The pranks were described in a Washington Post story.
The Post said in one of the pranks friends held down a classmate believed to be gay while a young Romney repeatedly clipped his hair while the victim screamed for help.
"I don't remember that incident," Romney told Fox News. "I tell you I certainly don't believe that I ... thought the fella was homosexual. That was the furthest thing from our minds back in the 1960s. So that was not the case. But as to pranks that were played back then, I don't remember them all but again, high school days -- if I did stupid things I'm afraid I gotta say sorry for it."
The Post said the attack on the gay student was confirmed by five classmates who said it was "senseless, stupid, idiotic" and "vicious."
Romney also allegedly shouted "Atta girl!" when another supposedly gay student tried to speak up in class, among a series of other pranks, the report said.
The candidate said his propensity for pranks changed when he met his future wife Ann in high school, CBS reported.