Article I, Section 8, Clause 15
To provide for calling forth the militia to execute the laws of the union, suppress insurrections and repel invasions:
Article II, Section 2, Clause 1
The President shall be Commander-in-Chief of the Army and Navy of the United States, and of the militia of the several States, when called into the actual service of the United States;
Now what is interesting is that Congress has to depend upon the President to sign the bill that they pass in order for it to become law.
The Congress can of course, override that refusal, and thus the President is "forced" to lead the "militia" as the Congress has ordered via their enumerated power.
His refusal may then be grounds for impeachment.
I hope this is reason for the legislation Rep. King as introduced. I have written my congressman 3 times and suggested the same.
Good test for the 2nd Ammendment. Calling up the National Guard undermines the word Militia and gives the lefties more ground.
I would be willing to serve.