This week's bizarre revelation by the IRA that it had offered to shoot Robert McCartney's killers was just the latest in a series of miscalculations by republicans. Chris Thornton reports

It must have made sense to someone. Accused of harbouring the killers of Robert McCartney, the IRA considered that the best way of absolving themselves, of showing they were better than that, was a proposal to kill the suspects. Or at least shoot them a little and then, this week, tell everyone about it.

"It was," an acute Northern observer said witheringly, "like the UDA at their daftest." There can be no crueller criticism for a movement that was once without doubt the most sure-footed stroller through unpredictable conflict and the strange byways of the peace process.

The UDA, the largest of the IRA's loyalist foes, has long had the reputation of being deadly but a little dumb. Prone to making mistakes. No one used to say that about the IRA. Even when they made their own errors and killed the people they didn't mean to kill, it was hard to forget the polished cunning and often strategic brilliance at the heart of the Provos.

These are changed times, indeed. The centenary year of Sinn Fein, barely into its third month, seems to have involved little more than republicans stumbling from one bad episode to another. If the IRA robbed the Northern Bank, they fundamentally miscalculated the reaction of Bertie Ahern. If they shipped the money from that robbery south, they also miscalculated the risk involved from Garda investigators and the effect that TV pictures of sackfuls of money would have.

Sinn Fein miscalculated by attempting to argue that the 1972 killing of Jean McConville, a mother of 10, wasn't a crime. And when some IRA members murdered Robert McCartney, republicans miscalculated from the very start.

Hours after Mr McCartney, a 33-year-old father of two, died from stab wounds to the chest at the end of January, youths in the Markets district of Belfast started throwing bricks at investigating police.

Alex Maskey, who hopes to win a Westminster seat in the area in May, defended the rioters, claiming they had been provoked by unnecessary and heavy-handed tactics from the PSNI. He denied the IRA was simply trying to cover the tracks of its members. Mr Maskey, as the first republican Lord Mayor in the one-time unionist citadel of Belfast, is a living icon. Like much of Sinn Fein, the subsequent admissions that have been dragged from the IRA, have left him tarnished. The Reverend Ken Newell, the soft-spoken and forthright leader of Irish Presbyterians, a man who has attempted to build bridges between republicans and Protestants and is not above criticising the DUP, visibly wounded Mr Maskey on BBC television recently by patiently telling him that many people no longer believe what he has to say.

Of more fundamental concern to Sinn Fein is the response of their own people. Mr McCartney was one of their own, a Sinn Fein voter in inner Belfast, where the party has been at its most resilient.

As Mr McCartney's remarkable sisters have subsequently shown, the episode has thrown up fundamental questions for republican supporters. Ten years after they first declared an end to military operations, what allowances are they prepared to make for "ceasefire soldiers"?

"I always thought they were an honourable army," said Paula McCartney, who grew up in the Short Strand during the Troubles and still lives there. "There were certain things they did, but in some ways they could be justified because there was a conflict. But this is senseless. If these people believe they're accountable to no one, it's going to send a message, not just to this community, but communities across the North, that the IRA can't control their members. Which is why a court of law is needed to publicly acknowledge when a crime is committed."

Martin McGuinness, Sinn Fein's chief negotiator, argues the intense and critical coverage of this week's IRA offer to shoot the McCartney suspects has only shown the "enormous gulf between the media - the establishment - and ordinary people on this issue". Since republicans tend to band together in the face of criticism, he may have a point. But there is no doubt that Sinn Fein remains deeply concerned about the effects of the episode.

If Paula McCartney carries through with her pledge to run for Belfast City Council if no one is made accountable for the murder of her brother, the ripple effects for Sinn Fein could be enormous. Even if she pulls in a few hundred votes in the Short Strand, she would be likely to cost Sinn Fein their only seat in a unionist-dominated area, a seat that took them years of work to narrowly capture in 2001.

The loss of that seat could leave Sinn Fein short of enough votes to return to the Lord Mayor's parlour, and so one of the most powerful symbols of the republican political advance would be lost for at least four years.

However, Sinn Fein is by no means in anything like full flight. They are almost certain to win at least one additional seat in the British general election which is expected in May and could conceivably - off a very good performance - take all three of the SDLP's remaining seats and utterly erase nationalist participation at Westminster.

Northern nationalists may have doubts about republican actions, but Orange v Green is still the over-riding factor for many people when they enter the polling booth, and Sinn Fein still represents the stronger opponent for unionists.

Even in the current storm, they appear to have been more effective than the SDLP, engendering enough doubt about the Northern Bank robbery where it counts. A Belfast Telegraph/BBC Newsnight poll this week showed that the largest block of Northern Catholic opinion, 44pc hasn't made up its mind about who robbed the bank.

Nothing demonstrated Sinn Fein's resilience more than the publicity coup of the McCartney sisters' appearance at the ard fheis, the lasting image before yesterday's by-election. Nevertheless, the turmoil that is underway in republicanism can be measured by the way IRA feels obliged to return again and again to the McCartney murder. Six IRA statements have already been issued this year, three of them gradually drawing out what the Provos know about the killing.

The most recent was the most puzzling for many people - the IRA's saying, as a matter of course, that it had offered to shoot the suspected killers of Robert McCartney but that the family had refused. The committee that is P O'Neill apparently did not see or care that the proposal to lynch their own would bring more criticism down upon them.

For some, the statement fed the conspiracy theory that the Sinn Fein leadership is content to see, in the words of one commentator, "a perfect storm" brew up over the IRA in order to force the issue of its continued existence. Or it may be that the IRA could have foreseen the reaction, but decided that it was the most effective way of showing reluctant witnesses to the murder that the killers no longer enjoy their protection. In the short term at least, those witnesses have the only means of getting the IRA off the hook.

For republicans, the most telling episode has been Gerry Adams's decision to pass the names of republicans - albeit indirectly - to police. "It was an extraordinary thing," said John Kelly, a former IRA and Sinn Fein Assembly member. "There were people murdered for less, like poor Jean McConville. What Adams did is more significant than what the IRA said. I suppose it indicates how much they are in a corner."

So Adams now goes to America for St Patrick's Day with a peace process that has changed utterly. "I'm watching politicians trying to predict something that's never happened before," says Paula McCartney in her living room in the Short Strand. "No one can predict the outcome." That includes the IRA's one-time master strategists.

* Chris Thornton is a political correspondent for the Belfast Telegraph.