"It's not about zingers," O'Donnell said.

"A zinger might be just something funny, a comedic line, something to sort of break the monotony of the debate to try and capture the imagination," he said. "It's something that's sort of shoehorned into the debate.

"But a good line, Reagan's line about his opponent's youth and age, not making that an issue, a good line is a substantive line that does capture the imagination of the press and the audience, to overrun and deliver the message that you want and do it at the expense of your opponent."