Complaints of media mistreatment have become more common from the Republican lawmaker in recent days. During an interview that aired Sunday on Fox News, Ryan said it "goes without saying that there's definitely media bias."

"We expected media bias going into this," Ryan added.

Asked to provide examples where the campaign had been wronged, Ryan said he wasn't going "to go tit for tat or litigate," but that "as a conservative, I've long believed and long felt that there's an inherent media bias."

"And I think anybody with objectivity would believe that that's the case," Ryan said.

Ryan's frequent complaints of media bias come despite Romney adviser Ed Gillespie saying last week the campaign has a "no whining rule" about media coverage.

"We have a no whining rule in Boston about coverage in the media," Gillespie told Fox News. "We just deal with the facts.”

He added that the campaign believed "that big choice will overcome all of this horse race political analysis you see in the media on a day-to-day basis."