It appears this drive of the feds to assert more control over the NG has been going on some time. Sadly, the Republicans are just as complicit as the Dems in this.. Here is a useful piece on the subject from 2007:
Governors lose in power struggle over National Guard
By Kavan Peterson, Staff Writer
A little-noticed change in federal law packs an important change in who is in charge the next time a state is devastated by a disaster such as Hurricane Katrina.
To the dismay of the nation’s governors, the White House now will be empowered to go over a governor’s head and call up National Guard troops to aid a state in time of natural disasters or other public emergencies. Up to now, governors were the sole commanders in chief of citizen soldiers in local Guard units during emergencies within the state.
Full piece here:
http://www.stateline.org/live/details/story?contentId=170453
Given that the Governors of several States are named the Commander in Chief of [their State’s] National Guard by their State Constitution (ex: NM), neither the Senators nor the Representatives of such have the authority to cede that authority to the President.