As he cultivates the impression that he is standing on his convictions in the partial-birth abortion fight, Rick Santorum is in reality doing just the opposite.
Rick Santorum's convictions support the right to partial birth abortions. 
mnli hypothesis: Rick Santorum's convictions support the right to partial birth abortions.  premise: As he cultivates the impression that he is standing on his convictions in the partial-birth abortion fight, Rick Santorum is in reality doing just the opposite.