Missouri Gov. Jay Nixon has vetoed legislation that would have made it a crime for federal agents to try to enforce gun control laws.

Nixon, a Democrat, announced the veto Friday. He noted that the U.S. Constitution generally gives supremacy to federal laws over conflicting state ones.

The bill would have made it a misdemeanor crime for federal agents to attempt to enforce any federal gun regulations that "infringe on the people's right to keep and bear arms." It also sought to invalidate some specific federal laws, including a 1934 law that imposed on tax on transferring machine guns or silencers.

The measure also would have made it a misdemeanor to publish the names of gun owners. Nixon said that would have violated federal free speech rights.