Rick Santorum's win in Tennessee came in one of the most conservative, most heavily evangelical, most religion-focused and most anti-abortion Republican primary electorates to date - all among the groups on which the former Pennsylvania senator has focused his appeal.

If Santorum's win was less wide than might have been expected, it's because another candidate, Newt Gingrich, also held appeal to some of these same groups. While Gingrich finished third, he looks to have taken enough votes from Santorum to keep Mitt Romney closer than he'd otherwise have been.

Three-quarters of Tennessee voters were evangelicals; 41 percent of them voted for Santorum, with 24 percent apiece for Romney and Gingrich. Three-quarters said it mattered to them that a candidate shares their religious beliefs, including 44 percent who said it matters a great deal. In the latter group, 51 percent backed Santorum, 24 percent Gingrich, 17 percent Romney.

Seventy-two percent were conservative, and 41 percent described themselves as very conservative; Santorum won the former group with 40 percent support, the latter with 47 percent. Romney won just 19 percent of very conservatives, continuing his struggles there. Similarly, among the strongest abortion opponents, Santorum won 48 percent support, Gingrich 25 percent - and Romney just 16 percent. Indeed, in a direct measure, 48 percent of Tennessee GOP primary said Romney is not conservative enough, compared to just 17 percent who said that about Santorum, and 23 percent about Gingrich.

Romney did far better non-evangelicals and moderates, but they were few in number in Tennessee. Among voters not concerned with shared religious beliefs he won by 19 points - but they made up barely a quarter of the electorate.

The gap between electability and empathy, apparent in states as disparate as Ohio and Vermont, showed up in Tennessee as well. Forty-three percent named Romney as the most likely candidate to defeat Obama in November, about double the number who picked either Santorum or Gingrich alike. But fewer than half as many said Romney understands the problems of average Americans - just 19 percent, trailing both Santorum and Gingrich, at 32 and 26 percent each.

Romney beat Gingrich and Santorum by 9 and 16 points, respectively, among voters who picked electability as the most important candidate attribute. But that margin was far narrower than in states where Romney's prevailed. In contrast, among the 37 percent focused on a candidate who is a "true conservative" or has "strong moral character," Santorum trounced Romney, 56-11 percent.