Gordon Brown may be about to back down on efforts to secure 42-day detention for terrorist suspects.
Reports are circulating that the government is unwilling to use the Parliament Act to force the bill past the Lords, who are sure to vote against it.
Without the use of the Parliament Act to overrule the Lords, the bill will definitely fail.
The climbdown follows desperate attempts to get the legislation through the Commons, a feat Mr Brown only accomplished by introducing a raft of concessions and, controversially, with the help of DUP MPs.
In an interview with the Times today, the former assistant commissioner for special operations at Scotland Yard, Andy Hayman, gave a clear indication of discomfort at the bill among senior police officers.
"It would have been my job to make these proposals work, but just trying to understand them gives me a headache," he said.
"The draftsman's pen has introduced so many hoops to be jumped through that a police case for detaining a terror suspect will become part of the political game."
The Liberal Democrats welcomed the move.
"This is the first sign that Gordon Brown is beating a retreat on this deeply unpopular measure, which is opposed by just about everybody including huge swathes of his own party," said Lib Dem home affairs spokesman Chris Huhne.
"As we see from former counter-terrorism chief Andy Hayman's comments, even many of those in the security services who support longer detention without charge are opposed to this fudged and deeply flawed bill."
The Conservatiuves said the reports put national security in "the worst of all worlds".
"In June Gordon Brown threw the kitchen sink at getting this vote through the House of Commons claiming it was indispensable," said shadow home secretary Dominic Grieves.
"Now he is briefing that he will not press it through. It is clear that Gordon Brown is someone who puts his interest before the national interest."
In a separate development, aides to London mayor Boris Johnson have been forced to deny reports he will block the appointment of potential police commissioners who supported the plans.