The President's Duty in Cases of Domestic Violence in the States
SECTION 3. He shall from time to time give to the Congress Information on the State of the Union, and recommend to their Consideration such Measures as he shall judge necessary and expedient; he may, on extraordinary Occasions, convene both Houses, or either of them, and in Case of Disagreement between them, with Respect to the Time of Adjournment, he may adjourn them to such Time as he shall think proper; he shall receive Ambassadors and other public Ministers; he shall take Care that the Laws be faithfully executed, and shall Commission all the Officers of the United States.
See Article IV, § 4, Guarantee of Republican Form of Government, and discussion of “Martial Law and Domestic Disorder” under Article II, § 2, cl. 1.