The intent of the supremacy clause is not to subordinate the states to the federal government; rather, it affirms that one body of laws binds the country. In fact, all national and state government officials are bound by oath to uphold the Constitution regardless of the offices they hold. Yet enforcement is not always that simple.
This shows even with a head government there still isnt always a full control of states and if some didn't want to start following the some of the US constitution they wouldn't necessarily be stopped by anyone. You have to find a middle ground with many of these states to get them to continue following.