What power does the supreme law have over other laws?

The Supremacy Clause of the Constitution of the United States (Article VI, Clause 2), establishes that the Constitution, federal laws made pursuant to it, and treaties made under its authority, constitute the "supreme Law of the Land", and thus take priority over any conflicting state laws.

Explanation:

both the house and senate must approve of the conference report. after a bill has been approved by both the house and senate in identical form, it is sent to the president. if the president vetoes a bill, congress may attempt to “override the veto.”