I call that the "drug warrior mentality".
They are one-issue Republicans.
There are similarities between the abortion and drug issues. Abortion and drugs are like most issues that we confront in that there are conservative principles that exist on each side. There exists tension and usually even direct conflict between these competing conservative principles.
So, it is only natural that conservatives fight with eachother about these issues and is is only natural that each side in each such fight will feel that it holds the genuinely conservative ground.