(CBS News) With a and previous victories in Ohio and Michigan, Mitt Romney is proving to be a formidable candidate in the Midwest.
Romney was greeted by a very different electorate in Illinois than inand last week. Just 29 percent of voters in Illinois described themselves as very conservative; that percentage was 42 percent in Mississippi. Four in 10 Illinois voters were white evangelicals -- about half the percentage in the Alabama and Mississippi electorates. In Illinois, more than a third of voters indentified as moderate or liberal.
Romney won the support of both men and women, although the race was a bit closer among women - 46 percent of women backed Romney, while 37 percent voted for Santorum. Santorum has fared well with women in some recent contests, winning the women's vote in both Alabama and Mississippi last week. Very conservative women in Illinois were more likely to vote for Santorum over Romney.
Romney beat Santorum among Illinois's conservative voters by eight points, but Santorum prevailed among those who described themselves as very conservative, a group Santorum has performed well with in past contests.
While Romney lost the very conservative vote, he did win the support of Tea Partiers.
As he has in other states, Romney performed especially well with higher income voters and college graduates. But Romney also made inroads among those without a college degree; They went 41 percent for Romney, and 38 percent for Santorum.
Romney continues to struggle with evangelical voters, a group that has supported Rick Santorum in recent contests. Those voters backed Santorum in Illinois as well, 46 percent to 39 percent for Romney. But Romney won the Catholic vote by a large margin, 53 percent to 30 percent for Santorum.
Electability and the economy have been strengths for Romney throughout much of this campaign, and that continued in Illinois. Among voters who said defeating President Obama was the most important candidate quality, a whopping 74 percent backed Romney. Santorum was way back in second with just 17 percent. When asked directly which candidate was the most likely to beat President Obama, six in 10 picked Romney.
As in previous primaries and caucuses, the economy was the main issue on Illinois voters' minds, and 52 percent of these economy voters went for Romney, followed by Santorum with 31 percent.
In contrast to recent contests, Illinois voters saw Romney as the candidate who best understands the problems of average Americans (36 percent). In Alabama and Mississippi, voters chose Gingrich. Even in Ohio, a state that Romney won, just 22 percent of voters said he was the candidate who understood Americans' problems; More voters related to Santorum (34 percent) in that state.
Many Illinois voters think Romney lacks conservative credentials - 42 percent said his positions on the issues are not conservative enough. Still, about as many (44 percent) said his positions on the issues are about right. But these voters find fault with Rick Santorum as well: a third said Santorum's issue positions were too conservative.
While Romney has been having trouble with the more conservative wing of the Republican party, Santorum has been unable to win in states that are more moderate ideologically and have fewer evangelical voters.
Feelings About the Candidates and the Race
The exit poll data suggests some dissatisfaction among both Romney and Santorum's voters with their own candidate - but also with his primary opponent. While about four in 10 Romney and Santorum voters say they strongly favor their candidate, 47 percent of Romney's voters and 44 percent of Santorum's say they like their candidate but have reservations about him.
In Illinois, it doesn't appear there was much opportunity for voters to switch from one candidate to the other. Most Santorum voters find fault with Romney ideologically: 67 percent of Santorum voters say Romney's positions on the issues are not conservative enough. And 51 percent of Romney's supporters think Rick Santorum's positions on the issues are too conservative.
While both Ron Paul and Newt Gingrich say they have no intention of withdrawing from the race, if the race was between the two frontrunners, Mitt Romney and Rick Santorum, then Romney would have led with an 8 point margin, 48 percent to 40 percent.
Most Illinois voters are content with a long primary battle if their candidate would emerge as the nominee. Two in three say that they would prefer their candidate wins the nomination even if it means the race would continue for months. Just 31 percent say they would like to see the race end soon, even if that means their candidate loses.