Is immigration a monster issue?

Hugh Hewitt proclaims that immigration and border security could cause a massive split in the GOP. I have my doubts.

I know that it is an issue. So are abortion, tax cuts, Iraq, the environment and the federal judiciary. I imagine it has a higher profile in California where Hugh lives. And I know that opinion polls show it to be a concern and that the recent protests have raised the visibility of the issue.

I just have a real hard time believing that the level of concern for most Republicans is that intense. Or that the extent of disagreement within the party is very great.