Proposed Legal Memorandum for Federal Takeover?

Can someone explain this to me? I see the words, but I need help understanding the story behind this story:

An emerging power struggle
Behind the scenes, a power struggle emerged, as federal officials tried to wrest authority from Louisiana Gov. Kathleen Babineaux Blanco (D). Shortly before midnight Friday, the Bush administration sent her a proposed legal memorandum asking her to request a federal takeover of the evacuation of New Orleans, a source within the state's emergency operations center said Saturday.

The administration had sought control over National Guard units, normally under control of the governor. Louisiana officials rejected the request, noting that such a move would be comparable to a federal declaration of martial law. State authorities suspected a political motive behind the request. "Quite frankly, if they'd been able to pull off taking it away from the locals, they then could have blamed everything on the locals," said the source, who is an adviser and does not have the authority to speak publicly.

Blanco made two moves Saturday that protected her independence from the federal government: She created a philanthropic fund for the state's victims and hired James Lee Witt, Federal Emergency Management Agency director in the Clinton administration, to advise her on the relief effort.

Why would there be a struggle for control of the National Guard? Could the blatant delay of help rendered to Louisiana be due to the federal government's attempt to usurp the state's authority? Or, are the fed's hands constitutionally tied until there is a "legal request" for help from the state? If someone knows, please share in the comments section.

UPDATE: I ran across this article that goes into the mechanics of Louisiana's State Emergency Operations Plan:

Why Didn't Louisiana Follow it's Required Emergency Plan?
September 4, 2005
Joseph Ranos

1) Why Didn't Louisiana Follow it's Emergency Plan? Why isn't anyone talking about this?
2) Why hasn't anyone mentioned that a Pre-Requisite for a Federal Response BY LAW is that State Law is Executed and the Emergency Plan is Executed FIRST?
3) Why did the Governor abandon the City of New Orleans for the Safety of Baton Rouge, before the Plan was Executed?
4) Why, when the federal Government was acting in accordance with the Stafford Act, did the State of Louisiana, by its Governors acts, delay making requests when being told this storm was going to hit?
5) Why did Mayor Nagin or Governor Blanco, delay while sleeping on it Saturday night, the Mandatory evacuation spelled out in the Louisiana Emergency Plan? Saturday the Mayor said he may order an evacuation tomorrow. (Sunday)
6) Where were the Parish Presidents who were signatories to the Louisiana Emergency Plan, and why did they fail in its Execution to the plan?
7) In the Parish failure to implement, why didn't the State take over as required by the plan?
8) Why weren't the Hospitals nursing homes, etc. evacuated since the plan required them to do so?
9) Why did the Mandatory evacuation only occur AFTER President Bush
called, and why did Governor Blanco stress that it was only after President Bush Called to urging the Evacuation order? Was she concerned for the Citizens, or was she grandstanding so she could blame the President if the Storm didn't hit?
10) Why were the Action Plan implementations required not done by the Local and State Government?
(Click here to continue article)

After reviewing all the information from the article and referenced documents, it would seem that Louisiana suffered a massive bureaucratic breakdown. It would not surprise me to hear that the chain of command broke down somewhere between the state level and the parish and/or city level. Sad.

...It is the duty of the [citizen] to protect his [state] from its government. - Thomas Paine

UPDATE (Part 2): I was reading an article from Paul Craig Roberts that:

A senior Bush administration official planted on the Washington Post the disinformation that FEMA could not act because the Louisiana governor had not declared a state of emergency. Hours after printing this disinformation, a red-faced Washington Post issued a retraction, which reads: "A Sept. 4 article on the aftermath of Hurricane Katrina incorrectly said that Louisiana Gov. Kathleen Babineaux Blanco (D) had not declared a state of emergency. She declared an emergency on Aug. 26."

It would seem that perhaps Louisiana got it right. For now, I'll wait and watch what happens. The truth will come out, eventually.

UPDATE (PART 3): Here's an article from Knight Ridder that seems to point to Chertoff, not Brown as the weak link when it comes to Federal bungling:

Chertoff delayed federal response, memo shows Knight Ridder - Tue Sep 13,10:00 PM ET
WASHINGTON - The federal official with the power to mobilize a massive federal response to Hurricane Katrina was Homeland Security Secretary Michael Chertoff, not the former FEMA chief who was relieved of his duties and resigned earlier this week, federal documents reviewed by Knight Ridder show. Even before the storm struck the Gulf Coast, Chertoff could have ordered federal agencies into action without any request from state or local officials. Federal Emergency Management Agency chief Michael Brown had only limited authority to do so until about 36 hours after the storm hit, when Chertoff designated him as the "principal federal official" in charge of the storm.

Chertoff Memo on Katrina Response [PDF] at Knight Ridder

Again, I'm still waiting for the dust to settle...