It does seem strange that Bush is picking someone that he must have known would not be popular with republicans.  Some have theorized before that perhaps Bush would pick an ultra-conservative, democrats would reject the person, and Bush would then pick someone who was still very conservative but seemingly moderate compared to the first pick.

Perhaps he's doing the opposite now.  Enough republicans will reject this pick and complain to their representatives, and then the reps will reject this pick, "forcing" Bush to pick someone more conservative, thus making his entire base happy - seeing your leaders follow your wishes is a more powerful positive message than leaders just doing stuff you like.  It would also demonstrate to the democrats that the republicans can make things happen, and force the democrats to watch their back and stay on the defensive.

Who knows.  Like I said, I don't really think this is right, but it's interesting to think about.