Brown, the canny and unscrupulous political operator, has done the maths. New Labour know that with a few compromises and bribes, the 42 Day Detention Bill will probably scrape through. And public opinion is divided.
Any bill will face stiff opposition in the Lords. But that is then and this is now.
So, instead of a vote on the merits or demerits of the proposed legislation, this has been spun as a vote to save the skin of the prime minister and a test of Brown's leadership.
The media are going along with this, happy to play the game. Turning what should have been a vote on principles into a vote of confidence in Brown.
Even some of the so-called Labour rebels will turn. This is not their time to challenge the government.
More importantly for Brown, this is totally wrong footing Cameron who now could be seen as on the wrong side of anti-terror laws.
Brown thinks at last he's got a winner with this one. But the way Brown and his New Labour cronies are playing politics with people and our civil liberties is shabby and shameful.