Because conservatives are already set on it. Conservatives have always been pro-criminalization because they have a financial motivation in the form of private prisons, and most likely the people pushing for it are in bed with the cartels. The best way to make a profit of something is to make it illegal - and as we see from the southern US border an the way to the southern top of South America, having what is effectively one giant narcostate that doesn’t have cares about traditional nation-state functions is incredibly profitable, and well armed.