Becoming a front-runner put the press spotlight on Santorum. Once reporters took him seriously, they did the Nexis searches on his speeches and Senatorial votes. Voila, controversial stuff emerged. It turns out Santorum has said some ugly stuff, particularly about contraception and the role of women. He has also been an avid pursuer of earmark projects for Pennsylvania; something the Tea Party strongly opposes.
Media scrutiny enabled voters to move beyond the "altar boy in the sweater vest" image that carried Santorum through the previous primaries and caucuses. At least some of the not-Romney vote seems to have decided Romney is better than Santorum, Gingrich or Paul.
