It isn't easy to get Republican and Democratic governors united against the White House, particularly in a campaign season.

But in sharply worded letters to Congress and to the Pentagon last month, 51 governors said they oppose language in the pending National Defense Authorization Act that would give the president broader authority to federalize the National Guard in times of domestic disasters.

The measure "violates more than 200 years of American history," Arkansas Gov. Mike Huckabee, a Republican, said during the National Governors Association's meeting in August. He called it part of a larger federal effort to make states "satellites of the national government."

NGA co-chairmen Gov. Janet Napolitano of Arizona and Gov. Tim Pawlenty of Minnesota, in an Aug. 31 letter, wrote that "[provisions] were developed without consultation with governors and encroach on our constitutional authority to protect the citizens of our states." Co-signing the letter were Governors Michael Easley of North Carolina and Mark Sanford of South Carolina, who co-lead National Guard issues for the NGA. Napolitano and Easley are Democrats; Pawlenty and Sanford are Republicans.

Their opposition questions a provision that received little attention when it was tucked into the House version of the massive Department of Defense authorization bill passed before Congress went on summer break. The bill is now in conference, and it is not clear whether the provision will survive a House-Senate compromise.

One Democratic House staffer said last week that "it really wasn't a controversial provision when it went through, but at this point I would say it is up in the air." A Republican source said it was never the intention to usurp the nation's governors, but that the NGA letters were getting the attention of the House leadership.

Josh Holly, a spokesman for the House Armed Services Committee, said House and Senate leaders had already met to identify the major issues in the defense authorization package, and a final bill could be passed out of conference as early as this week. He would not comment on whether the National Guard provision was expected to remain in the final legislation.

According to some reports, the White House is prodding Congress to change current laws regarding the administration's authority to federalize state National Guard troops, putting them under a central military command in the event of a domestic disaster. The Bush administration had promised after Hurricane Katrina to improve the government's response to such catastrophes.

"A lot of people have speculated that it was obviously in response to Hurricane Katrina," said David Quam, director of federal relations for the NGA. "When we caught this in the [House and Senate] bills, that's when we immediately said, we got an issue here … let's take the provision down and have this discussion. That’s where the governors are really coming from."

The White House did not return calls for comment.

An earlier Senate version of the Defense Authorization Act also included language similar to the House version, but it did not make it to the Senate’s final bill.

The president has authority to call up the National Guard in times of civil strife, insurrection, terrorism and attack by weapons of mass destruction. Typically, when there is a natural disaster, the Guard will be called up to duty by the governors, and depending on the situation, either the state or the federal government will foot the bill.

According to an interpretation of Title 10 of the U.S. Code, which would be modified in the Defense Authorization Act, the president does not have the authority to call up the National Guard for natural or manmade disasters. The changes in the pending legislation would give him that authority.

Doug Kmiec, law professor at Pepperdine University in California, believes the president could find the authority in existing law to activate the National Guard for domestic disasters, but this legislative effort is probably a way to make it easier for him to do so. He sees the governors' objections as largely territorial, and points out that the Guard has been activated routinely for war abroad and homeland security at home.

"The fact of the matter is, the National Guard is a component of the U.S Army and it has been for a good long time," he said.

But that doesn’t mean that the president should assume that the Pentagon is best positioned to command state National Guards in the case of a domestic, non-security-related disaster at home, said David Kopel, a fellow at the libertarian Independence Institute in Boulder, Colo.

"I think it's a terrible idea," Kopel said. "The National Guard is primarily a state entity, and if it is needed in a natural disaster, we have a history of the National Guard being used effectively in a state capacity by governors."

John Goheen, spokesman for the National Guard Association of the United States, said the effectiveness of state National Guards after Katrina was one of the few successes in the relief efforts and it might not be that way under a federal command.

"It could be paralyzed; you would not have the same state-to-state effort that was so successful in Katrina," said Goheen.

He said state Guard leaders talked to each other and were able to find specialized Guard teams from all over the country to respond to the post-Hurricane relief effort last year. "If the federal government were to centrally run this type of state response, it would not have gone as well."

But the Pentagon feels differently. It says the White House is seeking the authority to call up the Guard for future disasters, not to "wrest control of the National Guard" away from the governors, but to allow the president the discretion to pursue a "total force approach" to a serious domestic disaster, according to spokeswoman Lt. Col. Ellen Krenke.

But even some of the president's most vocal supporters are scratching their heads over this approach. James Carafano, a national security expert for the Heritage Foundation, called changing the law in this case "wrongheaded."

"The idea that you put a general in charge on horseback and everyone is going to listen to them – that's not how it works," he said, "Just transferring sovereignty from political leaders to military guys is just a huge mistake."