He can't. There is a reason Santorum is known primarily as a social values crusader. This is the stuff he most cares about and no matter how hard he or his advisers try, this sort of nonsense will come up again and again and again in a campaign. As as a general election nominee, Santorum would doom us to a landslide defeat that would take our House majority down with it.
Worse, Rick comes across as strident and judgmental and would alienate even many Republican voters who don't want anything to do with a candidate who wants to talk about why contraception is "not okay" and why we need to wage a war on porn. The guy is a walking electoral disaster waiting to happen.
People laugh now, but Pat Robertson actually did pretty well in the 1988 GOP primaries (one of his policy positions was to ban porn), came in second in Iowa and won some primary/caucus states. He'd have been an embarrassingly bad general election nominee and obviously would have doomed the GOP to defeat, but a certain segment of social conservatives voters (over a million before he dropped out) cast ballots for him anyway. In 2008 it was Mike Huckabee social conservatives gravitated to - not because Huckabee was particularly conservative when it came to government policy, but because they deemed him the most God-fearing candidate. Santorum is just another in the same mold and winning the same core of voters. He's only lasted this long because A)he was such an afterthought of a non-Romney candidate that most people ignored him for months, and B)our frontrunner, Romney, inspires pretty much nobody and is a terribly poor candidate himself who stands for pretty much nothing.
I want Newt to stay in till the end no matter what happens, mostly because I can't stand the thought of having to dig deep within myself and find a way to rally around either Mitt "the chameleon" Romney or Rick "lets talk about why contraception is not okay" Santorum.
They are very keen, in knowing that Santorum will be all too easy to beat. There is a Daily KOS group that has been formed that go from open primary to open primary, with orders to vote for Santorum, to get him nominated.
This is an actual plan. Because they have so much they can destroy Santorum with, that they are holding all of it until he gets the nomination.
Santorum as our nominee, will be an utter disaster, especially after the Left hits the polls in record numbers and also votes in more Democrats for both houses.