Romney's been practicing his debating skills.
In his first comments on that debate prep, he told George Stephanopoulos that:
"Sen. Rob Portman is a tough stand-in for a president who basically lies in debates.

“I think the challenge that I’ll have in the debate is that the president tends to, how shall I say it, to say things that aren’t true,” Romney said.
“I’ve looked at prior debates.
And in that kind of case, it’s difficult to say, ‘Well, am I going to spend my time correcting things that aren’t quite accurate?
Or am I going to spend my time talking about the things I want to talk about?”
From ABC News interview:
http://abcnews.go.com/blogs/politics/2012/09/exclusive-romney-on-debates-obama-will-say-things-that-arent-true/

Will Mitt Romney tell us how he plans to create 12 million jobs over the next 4 years in the debates?
After all the ads that Romney's campaign has run, Americans have some idea of who will be telling them the truth during the debates. It's laughable. Romney's afraid of Obama telling lies?
Romney's ads have said Obama took $716 billion from Medicare to give to Obamacare. This is untrue. Politifacts has said so but still, Romney persists.
Mitt Romney is handicapping himself before he enters the debates by saying the President will lie.
This debate between Romney and Obama won't be like Romney's debate against Rick Perry or the debate he has with himself.
It should be entertaining.
Romney told George Stephanopoulos the debates “may well be” the campaign’s make or break moment.
We'll see after the debates, if America can see more clearly what a 'bump in the road' candidate looks like from our rearview mirror.