Instead of going on the defense and trying to deny their lies, why not ask them to explain why they believe what they believe?
It's a nice, polite way to get them to "prove it." If it's the truth, their explanation will prove it. If it's a lie, their explanation will prove that, too.
For example, WHY did Harry Reid believe Romney didn't pay his taxes? We'd like to know more. What other info does he have other than one single opinion of a ghost person? Please, Harry, we'd love to know more about Romney's taxes. There needs to be more to this story than what you're saying. Keep talking! Tell us how this ghost found out what he knows. What expertiese does he have when it comes to taxes? More, more, more! We have question! Lots of them. If Romney disn't pay his taxs, we need to know much, much, more so we can get all this out in the open. Help us do that, Harry.
Surely, Harry, the opinion of one man certainly isn't enough to convict what could be an very honest man. Could you please gather just a little more information about this so we can understand why you're saying what you're saying? Thanks!
So, basically, call them on the lie and have them explain.
==
GOP needs to develop training on such tactics and techniques, because too many of their candidates get lost in interviews and debates. Recall Romney’s deer-in-the-headlights look when Steffie asked what he would do about a state banning contraceptions.
The Dems certainly are schooled on the alinsky tactics.