Rick Santorum's three wins in Colorado, Minnesota, and Missouri played a large part in raising his profile, but the whole of his surge is hard to explain with those wins alone. At YouGov, Michael Tesler finds that the Santorum surge is both a product of winning and a result of the intense national conversation over contraception:
To put this to words, respondents with the highest levels of "moral conservatism" began to respond to Santorum around the same time that the administration handed down the birth control mandate for religiously-affiliated institutions. Here is Tesler with more:
[M]orally conservative voters seem to have flocked to Santorum as they acquired more information about his similarly strong opposition to gay rights and abortion-an activation process that was probably accelerated by the influx of recent attention to these and other "culture war" issues in the news media.
Unfortunately for Santorum, this just increases the likelihood that he becomes pigeonholed as a "social conservative" candidate, without broad, general election appeal. Of course, this also happens to be truth-whether it penetrates the consciousness of actual Republican voters is, at the moment, up in the air.