Who is in the charge of upholding the supremacy clause of the United States constitution

The supreme AND state courts are in charge of upholding the supremacy clause. Though all three branches of government have to uphold the supremacy clause, the supreme court and state courts have to use judicial review to make proper judgement as to whether or not a law was passed that goes against the constitution.

Judges in every state are in charge of upholding the supramacy clause of the United States Constitution.

Explanation:

The Article VI, clause 2, also known as the Supremacy Clause, establishes that in case of conflict between federal law and State law, Federal Law MUST be applied. For that the constitution recognizes the jurisdictional review of the law that any state court can use to determine if a law is contrary to the federal law or the Constitution.

In the end that Supremacy clause make the Constitution of the United States, the milestone of the political and jurisdiction system.