Things Just Get Worse.

The measure, part of the massive National Defense Authorization Act, was also opposed by civil libertarians on the left and right. But 16 Democrats and an independent joined with Republicans to defeat an amendment by Sen. Mark Udall (D-Colo.) that would have killed the provision, voting it down with 61 against, and 37 for it.

"I'm very, very, concerned about having U.S. citizens sent to Guantanamo Bay for indefinite detention," said Sen. Rand Paul (R-Ky.), one of the Senate's most conservative members.

Paul's top complaint is that a terrorism suspect would get just one hearing where the military could assert that the person is a suspected terrorist -- and then they could be locked up for life, without ever formally being charged. The only safety valve is a waiver from the secretary of defense.

"It's not enough just to be alleged to be a terrorist," Paul said, echoing the views of the American Civil Liberties Union. "That's part of what due process is -- deciding, are you a terrorist? I think it's important that we not allow U.S. citizens to be taken."

Democrats who were also concerned about liberties compared the military policing of Americans to the detention of Americans in internment camps during World War II.

"Congress is essentially authorizing the indefinite imprisonment of American citizens, without charge," said Sen. Dianne Feinstein (D-Calif.), who offered another amendment -- which has not yet gotten a vote -- that she said would correct the problem. "We are not a nation that locks up its citizens without charge."

Backers of military detention of Americans -- a measure crafted by Sen. Carl Levin (D-Mich.) -- came out swinging against Udall's amendment on the Senate floor earlier Tuesday.

"The enemy is all over the world. Here at home. And when people take up arms against the United States and [are] captured within the United States, why should we not be able to use our military and intelligence community to question that person as to what they know about enemy activity?" Sen. Lindsey Graham (R-S.C.) said.

"They should not be read their Miranda Rights. They should not be given a lawyer," Graham said. "They should be held humanely in military custody and interrogated about why they joined al Qaeda and what they were going to do to all of us."

In criticizing the measure, White House officials said that it would cause confusion and interfere with a counterterrorism effort that has been remarkably successful since Sept. 11, 2001 -- across two administrations.

"It is likely that implementing such procedures would inject significant confusion into counterterrorism operations," the White House argued in a Nov. 17 statement.

Further, it contended:

This unnecessary, untested, and legally controversial restriction of the President's authority to defend the Nation from terrorist threats would tie the hands of our intelligence and law enforcement professionals. Moreover, applying this military custody requirement to individuals inside the United States, as some Members of Congress have suggested is their intention, would raise serious and unsettled legal questions and would be inconsistent with the fundamental American principle that our military does not patrol our streets. We have spent ten years since September 11, 2001, breaking down the walls between intelligence, military, and law enforcement professionals; Congress should not now rebuild those walls and unnecessarily make the job of preventing terrorist attacks more difficult.

A White House official said the administration stands by the veto threat. "We take this very, very seriously," the official said.

Both FBI Director Robert Mueller and Director of National Intelligence James Clapper backed up the White House with letters sent to congressional leaders. Clapper echoed the charge that the measure creates uncertainty and added that it could prevent intelligence operatives from getting critical information from suspects.

And although the measure allows the secretary of defense to waive it, both Mueller and Clapper said that could prove unworkable in the real world.

Mueller added that it could even stop the FBI from investigating individuals who fall under the definitions of suspected terrorist in the measure.

The 2012 National Defense Authorization Act would authorize defense spending on military personnel, weapons and war. The first draft of the bill won support from both parties in Congress in October, passing out of the Senate Armed Services Committee with just Udall dissenting. A similar House bill allocating $690 billion for the Pentagon passed in May, without the controversial measure. It could be changed when the differing versions are merged, if Congress desires.

The detention provision whipped up a furor in both parties, with Senate Majority Leader Harry Reid (D-Nev.) having already text delayed the vote over it.

The final vote showed bizarre fractures among Democrats, erasing the usual barriers between conservatives and liberals. The 16 who voted for the harsh detainee rules were Sens. Bob Casey (Pa.), Kent Conrad (N.D.), Kay Hagan (N.C.), Daniel Inouye (Hawaii), Herb Kohl (Wis.), Mary Landrieu (La.), Carl Levin (Mich.), Joe Manchin (W. Va.), Clair McCaskill (Mo.), Robert Menendez (N.J.), Ben Nelson (Neb.), Mark Pryor (Ark.), Jack Reed (R.I.), Jeanne Shaheen (N.H.), Debbie Stabenow (Mich.) and Sheldon Whitehouse (R.I.). National defense hawk and independent Sen. Joe Lieberman (Conn.) also voted in favor of the tougher language.

"It's one of those things where ... it's bipartisan on both sides. Levin's not on the same page as the White House. We've got our own internal differences; Paul and Kirk don't agree with Graham," said a senior GOP aide just before the vote. "Everybody's trying to do the right thing. There's just a difference of opinion."

Even though Paul was joined only by Sen. Mark Kirk (R-Ill.) on his side of the aisle, the issue was contentious at the Republicans' weekly caucus lunch.

Sen. John McCain (R-Ariz.) emerged from the meeting -- where former Vice President *** Cheney was in attendance -- saying his colleagues had "a spirited discussion" about Udall's amendment, and predicted nearly all Republicans would oppose the amendment, as they did.

Update 10:30 p.m.

Sen. Menendez later sought, and was granted, unanimous consent from the Senate to change his vote. He is now recorded as supporting the Udall amendment, with the final tally changed to 38 to 60.