Thompson in one of the pre-NH debates (Saturday or Sunday– they run together to the extent I still remember them) did strongly criticize immigration reform and define amnesty as letting illegals stay here, which is an implicit criticism of McCain. However, he has not done so in a personal way and he and McCain agree on most other issues so the differences there are not stark. Aside from their friendship I think there are practical reason to aim his fire elsewhere. He’s got to knock off Huckabee to grab social conservatives in SC and scoop up what’s left of the Romney ones (Romney may be pulling out there according to this). But time is running out for him and it does not sound like he is dramatically changing the tenor of his approach.