Who's expanding the Republican electorate?

The Democratic electorate is shrinking, as I explained in this blog post, by the secession of moderates and conservatives from the party’s nomination process. So what is happening to the Republican electorate? It’s expanding, primarily but not entirely by the addition of more evangelicals.

Here are the numbers, extrapolated from exit polls, showing in rounded-off thousands the total vote in the Iowa caucuses and New Hampshire and South Carolina primaries, the turnout of evangelicals (estimated for New Hampshire in 2008) and of non-evangelicals.