Mr Peter Mandelson will feel the full force of unionist fury in the House of Commons this afternoon as he commits the British government to the implementation of the Patten proposals for policing in Northern Ireland.
However, in a rearguard action the First Minister and Ulster Unionist leader, Mr David Trimble, is expected to cast the political spotlight on IRA decommissioning and the growing threat to the power-sharing Executive. Sources close to Mr Trimble last night confirmed that he regards January 31st as the effective deadline for a start to IRA decommissioning.
If Gen John de Chastelain has not announced a start to the disarmament process by that date, senior unionists say, they expect Mr Mandelson to declare a "default" and suspend the institutions established under the Belfast Agreement.
Describing concessions wrung from Mr Mandelson on Patten as "thin gruel", UUP sources said today's Commons statement confirming that the RUC's "Royal" title will be scrapped in favour of The Police Service of Northern Ireland would compound Mr Trimble's problems in the build-up to the reconvened meeting of the Ulster Unionist Council on February 12th.
Mr Mandelson is expected to announce his broad acceptance of the 175 Patten proposals, while telling MPs that full implementation of the commission's recommendations, particularly those designed to establish a proper religious balance in the force, could take up to 10 years.
However, Mr Mandelson is expected to try to ease the pain for unionists with modest concessions in two key controversial areas: the cap badge and insignia, and the role of the proposed district police partnership boards.
Pro-RUC campaigners, who last week handed a 350,000-name petition into Downing Street opposing the proposed changes in the RUC's title and emblems, will be deeply disappointed if, as seems probable, Mr Mandelson does not announce that he will retain the crown and harp on the cap badge.
However, there are indications that the NI Secretary may disagree with Mr Chris Patten's conclusion that national symbols should not be associated with the new police service, and that he will leave the creation of a new symbol for the service to the 19-member Police Board due to replace the Northern Ireland Police Authority later this year.
Sources said last night that any recommendation from the new board would be subject to the approval of the Secretary of State.
Unionist politicians appear resigned to having lost the fight against the creation of district police partnership boards (DPPBs), which Mr Trimble and his colleagues fear could lead to direct paramilitary involvement in, or assumption of, local policing functions.
However, Mr Mandelson is understood to be determined that the legislation implementing Patten should contain very tight safeguards about the advisory nature of the DPPBs. Specifically, it is believed he will insist that any extra revenues raised on local rates for additional police services can be spent only on projects approved by local police commanders.
It is also possible Mr Mandelson might delay the introduction of the DPPBs' power to raise additional revenues to an estimated £6 million.
Mr Tony Blair will be hoping that today's inevitable row between Mr Mandelson and unionist MPs will be short-lived. However, the countdown to any IRA decision on decommissioning, and Mr Trimble's return meeting of the UUC, are set to be marked by further controversy in the Commons over British government so-called concessions to Sinn Fein, on office facilities and costs at Westminster, and on the "dual mandate".