I'd sooner explain quantum mechanics (which I couldn't) to a roomful of squirming second graders than attempt a bumpersticker defense of this contortion to maybe 75 million low-information, logically challenged voters:
The Romney campaign got the $716 billion figure from a July 24 Congressional Budget Office report, which measured the impact of repealing the health care overhaul law, which is known by many as Obamacare. But the report also notes that the projected $716 billion increase in Medicare spending if the measure is repealed does not signal a $716 billion decrease if the measure stays in place -- which is Romney's argument.
Yes, the passage makes sense. On the other hand it requires of the reader a complex leap from Point A straight to Point B--an impossible mental progression for those voters who haven't yet figured out, for instance, that government can create jobs, and indeed has.
All of which goes to the historical demonstration that the simpler the honest logic, the easier the counterpunching dishonesty--which is what every dictator and demagogue has always relied on.