A number of Republican 2016 presidential candidates are heading for a difficult moment on the issue of immigration reform. Here is how it will work:

1) It is commonplace among Republicans along the spectrum of opinion on the issue to say that the United States is not going to deport all 11 or 12 million immigrants currently in the country illegally. What that generally means is the United States is not going to deport any of those immigrants, barring some who have been convicted of multiple serious crimes.