Section 4. The United States shall guarantee to every State in this Union a Republican Form of Government, and shall protect each of them against Invasion; and on Application of the Legislature, or of the Executive (when the Legislature cannot be convened) against domestic Violence.If this doesn't violate the guarantee of a republican form of government, I don't know what does.
“To guarantee to every State in the Union a republican form of government; to protect each of them against invasion; and on application of the legislature, or of the executive (when the legislature cannot be convened), against domestic violence.”
Here, in recognition that self-defense is the reason society comes together to form a governing compact in the first place, the new government was charged with defense of its member republics and people from three threats. The first threat is from non-republican government; only republican forms can secure liberty. Republican forms of government are characterized by the rule of law, popular consent, and no monarchy or aristocracy. Madison wrote that “as long as the existing republican forms are continued by the states, they are guaranteed by the federal Constitution.” The only restriction is that they shall not exchange republican for anti-republican Constitutions.