I think what he is saying is that the conservatives who disapprove of the policy outnumber those who approve by 18%, but among independents, those who approve outnumber those who disapprove by 24%.
I saw another interesting statistic on the news today. Among the general public, 58% of those likely to vote approve of the policy. Among catholics, 57% of all catholics and 59% of catholic women favor the policy.
While this debate over contraception might be energizing the bible thumping republican base, it is largely a loser with the general voting public. So, while it might result in someone like Santorum gettin the republican nomination it will certainly not result in such a candidate getting elected.