Mitt Romney’s struggle with white evangelical voters doesn’t bode well for him as he moves through the GOP presidential primary, with Mississippi and Alabama just ahead.

In the five states so far where born-again Christians were a majority of GOP primary voters, Romney has trailed either Rick Santorum or Newt Gingrich among evangelicals by an average of 20 points, according to exit polls. About 4 in 10 born-again voters who were asked said it was deeply important that a candidate share their religious beliefs.

Still, exit polls also show an opening for Romney to draw a bit more of the evangelical vote. In Ohio and Tennessee, evangelicals who said shared religious beliefs are less important when choosing a candidate were significantly less likely than other evangelicals to see Romney as too moderate.

The key question for Romney is whether enough of these evangelicals are present in the contests ahead to make any difference for his candidacy.

In the 2008 Republican presidential primary, about three-quarters of Republicans in Mississippi and two-thirds in Alabama identified themselves as white evangelicals. Primaries in Mississippi and Alabama are set for Tuesday, with Louisiana to follow on March 24.

John Green, a University of Akron political scientist who analyzes religion and voting, said he noticed that Romney generally does better, although not well, among evangelicals in larger metropolitan areas. These urban born-again voters are found in greater numbers in states where Democrats and Republicans are more competitive, such as the Midwest.