One reason for Santorum’s struggles with non-evangelicals: He continues to underperform with fellow Catholics. After losing them in Michigan and Ohio, he turned in a weaker performance Tuesday than in either earlier state. Santorum attracted just 31 percent of Illinois Catholics, far behind Romney’s 52 percent. Indeed, Romney has outpolled Santorum among Catholics in every state where there has been enough of them for exit polls to measure, except Tennessee (where Santorum led by 1 percentage point.) It was probably a telling signal of how Santorum viewed his prospects with Catholic voters that he spent last Sunday campaigning in three Baptist churches in Louisiana rather than in Catholic parishes in and around Chicago.
Santorum ran no better than even among working-class voters who have generally provided Romney a tougher audience. In the exit poll, the two men ran about step-for-step among voters without a college degree, those earning $50,000 or less and those earning between $50,000 and $100,000.
The two constituencies that held for Santorum in Illinois were those that have most reliably bolstered him since his revived his candidacy with his three-state sweep on Feb. 7. Even amid his shellacking, Santorum still beat Romney among voters who identify as very conservative, with a solid 49 percent to 36 percent margin. He has carried those voters in seven of the nine states with exit polls that he has seriously contested since early February.
Most importantly for Santorum’s future hopes, he retained his hold in Illinois on evangelical Christians, outpolling Romney among them by 47 percent to 37 percent. He has now carried evangelical Christians in every state with an exit poll that he has seriously contested since Feb. 7, except Georgia, where they flocked to Gingrich. Still, Santorum’s evangelical margin in Illinois was well below his advantage with those voters in Ohio (17 points) and Michigan (16 points).
The patterns of support that Illinois reaffirmed Tuesday would leave Romney holding a strong advantage in states, many of them along the coasts, where evangelicals will likely comprise only about a third of the vote or less (and where affluent, better-educated voters will also loom larger), including Maryland, Connecticut, Delaware, New York, New Jersey and California.
But Romney’s inability to break Santorum’s hold on evangelicals means the former senator remains the favorite in interior states where those voters will likely cast at least half of the GOP ballots, including Missouri, whose caucuses began Saturday, Louisiana, Texas, West Virginia, Arkansas, Kentucky and probably North Carolina and Indiana (where no recent exit polls are available).
Still, if Romney can match his pattern in Illinois -- and win non-evangelicals by a much larger margin than Santorum captures evangelicals -- he might be able to surprise Santorum in states divided fairly closely between the two groups, such as Oregon, Nebraska and maybe North Carolina. For all the focus on Romney’s very real difficulty in capturing the most ardent conservatives, Santorum’s inability to reach beyond them looks like an even greater problem after his resounding defeat in another Midwestern battleground.