Does Krauthammer believe that the GOP will be drastically hurt by this?
I do not know. He said he was more concerned about the country than the GOP.
The real question is, will this motivate an already open border/pro Illegal democrat voting pool to not vote Republican. Since the GOP weren't going to get them anyway the answer is, who cares. Also, keep in mind, there are a ton of Dem and Independent voters who are equally furious over Illegal Immigration. As such, this more likely to help the GOP.