Other than the payroll tax legislation, the big news in the Senate this week is the defense authorization bill, traditionally seen as must-pass legislation. It seems like every year there’s some big controversy over this bill.  This time that comes in the form of a measure that would mandate indefinite detentions of terrorist suspects in military custody and open the door for those indefinite detentions to extend to US citizens.

The military would essentially have total control over detainees, and even with a dissipation of Al Qaeda they would be authorized to use the indefinite detention power over anyone they deem a dangerous threat to national security.

The Obama Administration has offered an ambiguously worded veto threat to the bill, but it’s unclear whether this threat specifically targets the indefinite detention provisions. And the President has already signed a prior defense bill with similarly troubling provisions.

With any defense bill there are lots of pending amendments, and the legislation could take the whole week. A list of amendments is here. But the most important one comes from Sen. Mark Udall of Colorado, who wants to strip out the indefinite detention changes. Here’s his statement:

While Udall strongly supports the overall defense bill, he has led the opposition to provisions dealing with military detainees because they were drafted in spite of the Pentagon’s opposition. The provisions remove the military’s ability to select the best venue to prosecute suspected terrorists and create legal ambiguity that would jeopardize the military’s anti-terrorism operations and detention practices.

“The United States Senate has a solemn obligation to our men and women in uniform to pass a Defense Authorization Act, but we also owe it to those fighting the war on terror to prevent rushed, untested and legally controversial limitations on their operations. I can’t support provisions that I believe will hurt our national security,” Udall said. “We haven’t had time to adequately consider these provisions. We need to know what our military and intelligence experts – and our men and women in the field – actually need to most effectively prosecute the war on terror, especially before we change detainee provisions that are already working. I’m urging my colleagues to support my amendment so we can prevent a White House veto, move forward with the NDAA and reach a workable resolution on the detainee provisions.”

Udall gave a long speech on the Senate floor itemizing his concerns. The full text of his amendment is here. He is whipping support for his amendment and already has 20,000 citizen co-sponsors. Udall writes in an email to supporters that “we are threatening to undercut the very principles provided to every American under the Constitution,” and that “These new regulations would make the U.S. military the judge, jury, and jailer of terrorism suspects and could prevent the FBI and state and local law enforcement from participating in the investigation.” He is leveraging the support of the White House even while they have remained circumspect. Since it’s in the interest of virtually every Senator to pass the defense bill and keep the military contractor gravy train flowing, using the threat of a veto is one of the few ways to affect the outcome.

Jeralyn Merritt has another series of amendments to the defense bill that need to be defeated. But the Udall amendment is basically the last chance for stopping an indefinite detention regime from passing the Senate. Udall does not have the full support of his party on this. Carl Levin and John McCain, the co-chairs of the Senate Armed Services Committee, have a WaPo op-ed defending the detention measures. They chalk it up to a “misunderstanding” about what the bill actually does. I’m not so confident.

There’s a conference committee with the House, some completely unrelated measures (like military chaplains performing same-sex marriages) that could derail the bill, and that vague veto threat from the President. But the best way to stop the indefinite detention regime is by passing the Udall amendment.