The knives are out again for David Trimble. In reality, they have never been otherwise since the coming into effect of the Belfast Agreement more than four years ago.
The First Minister and leader of the Ulster Unionists has fended off successive heaves against him since. Another direct challenge to his leadership will now be mounted in late September.
From an outside perspective, David Trimble is the best thing that ever happened to unionism. A joint Nobel peace laureate, he is respected and recognised internationally as the man who led his party out of the political blind-alley in which it had been trapped for decades. The world looks at Northern Ireland today and sees a polity that may be far from perfect. But the communities share power. Democracy - more or less - operates. Paramilitary violence is significantly reduced.
Mr Trimble's own people do not see it like this. The Belfast Agreement committed the paramilitaries to fully embracing the democratic process. But they remain active. On Thursday, the head of Belfast's police, Assistant Chief Constable Alan McQuillan, declared that the IRA and the UVF are orchestrating street violence. Extremists in both communities continue their murder campaigns. Racketeering, drugs and illegal alcohol proliferate in many of the areas controlled by the gunmen. Mr Trimble is perpetuating a fraud and an injustice on the electorate by remaining in government with Sinn Fein, claim his critics.
Their complaint is not without substance. All the fully democratic parties have bought into a pragmatic fudge with Sinn Fein in the Executive. Republicans are enjoying the fruits of legitimate power while they maintain their paramilitary machine. Other parties support the newly-formed police service while Sinn Fein refuses to take its places on the policing board or to fully legitimise the service.
It cannot go on indefinitely and Sinn Fein knows it. During the week Mr Mitchel McLaughlin tacitly acknowledged that Sinn Fein will buy into the PSNI in time. The implications of that for the Sinn Fein-IRA family are enormous. They cannot support both the police and an illegal paramilitary organisation on the same streets and at the same time.
The question is whether Sinn Fein's progress towards full political normalisation will move at a pace sufficient to enable the Agreement to survive. David Trimble may see off the leadership challenge next month. But the Agreement, in effect, will be put to the test before the people of Northern Ireland in the May elections. There is little doubt that as matters stand it will not be endorsed even by the small majority which favoured it in 1998. The coming months are crucial. The course to be adopted by Sinn Fein, as so often before, puts it in the pivotal position.