The Lord Chancellor, responsible for piloting the Bill through its crucial Lords' stages, plans to make a statement on the measure's future progress in the next week.
His unusual decision to speak out well before the Lords' Committee stage begins on 15 February signifies the gravity with which the threatened revolt is being viewed by the Government.
Lord Mackay has made a detailed study of last week's attacks by three former Home Secretaries, Lord Taylor of Gosforth, the Lord Chief Justice, and Conservative peers, and will attempt to use the statement to reassure critics. But there is private acceptance within the department that ground will have to be given on the Bill's detail.
Michael Howard, the Home Secretary, has already signalled that, subject to formal Cabinet approval, he would be prepared to compromise over the Bill's proposal for government-appointed chairmen of police committees. But the Bill is also at risk of losing its Lords' Third Reading over provisions covering justices' clerks, who advise lay JPs on the law, and decide on legal aid, bail and adjournments.