A next-day analysis of the Republican presidential primaries in Michigan and Arizona won by Mitt Romney underscores one of his weaknesses with his party's base, especially with the ascent of his now-chief rival Rick Santorum: He fares more poorly with born-again and evangelical voters than with nonevangelicals.
It was particularly apparent in Michigan, according to exit poll results analyzed by the Pew Research Center's Forum on Religion & Public Life. Voters who were polled could describe themselves as born-again or evangelical, regardless of their religious affiliation.
Fifty-one percent of self-described evangelicals in Michigan's primary voted for Santorum, Romney's top rival for the GOP nomination.
Romney, who is Mormon, got 35 percent of that part of the evangelical vote. Thirty-nine percent of Republicans who marked ballots in Michigan on Tuesday were white, evangelical and Protestant, Pew reported.
And nonevangelical voters in Michigan's primary? Romney was the choice of 45 percent; 30 percent picked Santorum, who is Catholic.
In Arizona, where 37 percent of those voting in the state's primary were identified as white evangelicals, Romney fared better.
He and Santorum, Pew reports, were "virtually tied" in their race for the evangelical vote — 35 percent for Romney, 37 percent for Santorum.
Romney, however, crushed Santorum among Arizona's nonevangelical voters, 54 percent to 20 percent.
In its analysis, Pew said Tuesday's contests continued Romney's pattern of support among evangelical voters. And it underscored the fact that Santorum continues to poll best among Republicans who say it matters a "great deal" that a candidate share their religious beliefs.
The Santorum campaign, in a Wednesday conference call with reporters, sought to underscore Romney's difficulties in wooing the religious base.
Though Santorum's focus on social issues that resonate with evangelical voters — from contraception to the separation of church and state — has been criticized by leaders in his own party, Santorum senior adviser John Brabender said the campaign welcomes discussion about the issues.
"We think everybody should be asked [about] social issues, " he said. "We don't mind the questions."