Why isn’t Santorum doing better among Catholics?

Analysts are crunching the numbers and looking at exit poll results, and have some conclusions:

It still is not clear whether Rick Santorum’s comments on religion in public life cost him a significant number of Roman Catholic votes in the Michigan and Arizona primaries.

The conventional wisdom seems to be that the comments did hurt him. Even Mr. Santorum understood that he might have made a mistake by saying last weekend that he wanted to “throw up” after reading John F. Kennedy’s 1960 speech on the separation of church and state. On Tuesday, Mr. Santorum said he regretted his choice of words.

In the Michigan primary, Mr. Santorum, who is Catholic, lost the Catholic vote to Mitt Romney, who is Mormon, 44 percent to 37 percent, according to exit polls. Because the two were virtually tied among Protestants, the Catholic vote effectively provided Mr. Romney with his margin of victory.

But the full story is not quite as simple as the basic timeline.

Mr. Santorum’s relative performance among Catholics was not so different in Michigan than it was in other early states, according to exit polls. His 37 percent of the Catholic vote was nearly identical to his 38 percent of the total vote. In Arizona, which also voted Tuesday, Mr. Santorum did better among Catholics (34 percent of the vote) than over all (27 percent).

That combination is similar to his relative performance among Catholics in the other early states with exit or entrance polls. In South Carolina, Florida and Nevada, his share among Catholics and his overall vote share were close enough to be within the polls’ margin of sampling error.

He received 17 percent of the total vote in South Carolina and 15 percent of the Catholic vote. In Florida, he received 13 percent over all and 10 percent of Catholics. In Nevada, he received 10 percent overall and 13 percent of the Catholic vote…

…So why hasn’t Mr. Santorum performed better among Catholics?

For one thing, his socially conservative message may play better with evangelical Protestants than any other group. For another, Catholics on average are more affluent than Protestants, and more affluent Republican primary voters have favored Mr. Romney over Mr. Santorum, independent of their religion.

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