They want the federal government to have absolute control of the drug laws so they can trade permission to use drugs for votes.
They may support the idea that there are some drugs the federal government should simply decline to criminalize but they will never accept an argument that there is any instance where it is simply not the federal government's perogative to regulate or prohibit anything they want.
They may argue that they people should be allowed to use medical marijuana, but they don't mean for anyone but the federal government to have the authority to say they can.
Prop 19 should be a big boost to getting out the Barbara Boxer voters.