Reform of the Royal Ulster Constabulary could be put on ice if the SDLP does not swiftly endorse the alternative Police Service of Northern Ireland, according to well-placed sources.
The warning emerged in Whitehall as ministers and officials assess the practical consequences of the standoff with nationalists and republicans over policing, and as Mr Peter Mandelson tries to win broad nationalist support for the legislation implementing the Patten Commission's proposals.
In a key Commons answer just before Christmas the Northern Ireland Secretary assured the SDLP leader, Mr John Hume, that the British government shared Patten's "baseline" on key policing issues. Mr Mandelson also promised the crown could not be retained in the new cap badge unless the SDLP agreed.
The Secretary of State and the Northern Ireland Office maintain they are "planning for success, not failure". However, well-placed sources have said postponing the reform programme is a serious possibility.
The first major casualty of any significant delay in implementing the new Police (Northern Ireland) Act could be the initial phase of planned 50-50 Protestant-Catholic recruitment for the service. Delay could also hit the creation of the new Policing Board and the formal change in title to the Police Service of Northern Ireland, due next September as the first wave of new recruits passes out.
The Policing Board, comprising 10 members from the parties in the power-sharing Executive, and nine independents, was expected to begin its operation in "shadow" form early next month. However, the SDLP leadership has ignored previous deadlines set by Mr Mandelson, and has so far given no commitment to nominate members to serve on the board.
There is growing suspicion in London that, despite Mr Chris Patten's endorsement of the new arrangements, the SDLP might not be prepared to do so ahead of the general election. The Irish Times has been told that if that proves to be the case Mr Mandelson might be forced to withhold commencement orders bringing key elements of the Patten reforms into play.
Referring specifically to the planned programme of early redundancies among existing RUC officers and the new recruitment campaign scheduled for late March, one insider said last night: "How can he (Mr Mandelson) lose personnel he already has, if he has no guarantee that replacements will be forthcoming from the nationalist community because the SDLP and the (Catholic) Church have not endorsed the new service?"
There is clear alarm in Whitehall at the possible impact of any decision to delay on the political and peace process as a whole. One source said unionists might thus be able to claim they had achieved the "moratorium" on policing reform briefly advocated, though never actively pursued, by the First Minister, Mr David Trimble.
However, the greater worry for ministers is that the SDLP's continued refusal to endorse the new police service might further weaken Mr Trimble's position and make more likely a fresh challenge to his authority at the Ulster Unionist Council late next month. Against that backdrop, sources say mid-January "really has to be decision time".
In what is seen as a confidence-building measure towards republicans, Queen Elizabeth has signed the Royal Prerogative of Mercy for four former IRA prisoners: Mr Angelo Fusco, Mr Patrick Campbell, Mr Paul Patrick Magee and Mr Anthony Sloan.