Start by asking the liar for example, would they cut all the things they know he would have to cut like, home interest, property taxes, state taxes, charity, disabled child, care, foodstamps etc etc. Then ask him what will he cut to pay for the 20% tax cuts across the board, when he says he want. He'll say he want, because that's a loser. But think of a response, if he says he will, like OH GOSH and say it loud.
But first Biden and Obama have to calculate and let the ordinance know, how much revenue would be lost by giving everyone that 20% tax cut and how much less revenue we'll get, if the rich gets that tax cut too. This would establish Romney tax plan does indeed come out to $5 trillion. Start out with this in the beginning of the debate and use the same tactics throughout.
Ask, are you for the dream act, DOMA, DADT, equal pay for women, Akin rape statement and anti abortion bill to force women to have the baby of a rapist, etc. If Joe or Barack want to get nasty, ask them would you force your daughter or wife to have the baby of a rapist? Ok no, but Joe and Obama could make that part of their statement. Don't forget, they are reaching for low information voters, who may not have heard about the anti abortion bill Ryan and Akin pushed and voted for. Same with Romney and healthcare plan included pre- existent conditions, his lies about medicare. State the PAGE in his book, or the date he made the statement that his HCR law could work nationwide. In other words, if they are going to lie, remind the viewing ordinance, what they supported and in Ryan's case, helped draft and voted for no abortion regardless of rape or incest. When they lie and they will, because anyway they go, they can't win if they tell the truth, and they can't win the undecided, or moderate vote if they are caught and exposed as liars in front of close to 60 million viewers. When they say they supported the things I listed above, even though their base doesn't care, it's the low information voters who make their decision based on debates. They will have been exposed.
With a liar, first ask them what they are for, and use their responses to back them in a corner. The most important way to back them in a corner, is to forcefully remind the ordinance with DATES when their opinions were different. Like, Gov, on this date, this date and this date, you said something different, or in Ryan's case, you voted for these things on this specific date/s. And state what those differences were. Which is it Gov, what you said on that date, or what you are saying now?
Catch them with their hands in the cookie jar, with that "blue pie all over their faces". A liar has to be trapped. I think this tactic will work, because a liar will continue lying and will also forget the lies they told. People must be reminded of the lies they told and are telling.
Oh, if Ryan says it's too time consuming and he doesn't have time to list what cuts he'll have to make, Joe Biden should say look, I'll give you some of my time, now go ahead tell us what you'll cut congressman Ryan.