A point must come where Northern Ireland politicians and the Northern Ireland public feel the game isn't worth the candle, that there is no point playing the politics of perpetual crisis - that it is just too wearying and dispiriting.

We haven’t got to that stage yet, but it must be getting close.

Martin McGuinness says £200 million (€281.8 million) might be sufficient to solve this latest impasse, but that's far from clear because there are so many questions and so much confusion about the financial arithmetic.

His comments at least indicate a willingness to get back into negotiation.

So, perhaps on the flight over on Tuesday or in New York on Wednesday between meeting potential investors, he and Peter Robinson might find the additional energy to discuss a workable solution.

Northern Secretary Theresa Villiers has said that if more money is required it isn't going to come from the British Treasury, because that would be unfair to British people hit by welfare cuts.

Existing resources

In other words, if Northern politicians want to make life that bit easier for welfare recipients, they must find the money from their existing resources.

Which would mean raiding the current budgets of other Ministers. So, where would the money come from - education, health, housing, jobs, the Irish language?

Following the agreement, Sinn Féin talked up how it got £564 million over six years - £91 million per year - to protect those who faced welfare cuts.

But now Sinn Féin seems to have discovered that that figure is perhaps £280 million short of what actually is needed to maintain benefits at current levels - notwithstanding that in the meantime Mr McGuinness appears to have reduced that figure to a nice round £200 million.

On Tuesday on BBC Radio Ulster's Nolan Show, former DUP finance minister Sammy Wilson and Sinn Féin MP Conor Murphy fought it out over what was pledged in the Stormont House Agreement.

Frequently there was more shade than light, but Sinn Féin seemed to feel it was somehow hoodwinked over welfare.

Mr Wilson insisted the agreement just could not have contained a cast-iron guarantee that there would be no change to welfare benefits because it was impossible to predict how many people would be seeking welfare benefits in the future.

At one stage Mr Wilson said in exasperated tone, “It is almost impossible to deal with you lot.”

The recurring response from Mr Murphy and from Sinn Féin generally over Monday and today was that current and future recipients of welfare benefits must and will be protected.

Fine mess

It’s a fine mess. By the end of this month, Westminster will be in effective “purdah” ahead of the British general election in May, with Northern Ireland politicians also in election campaign mode.

If there is to be a resolution it must happen quickly. Otherwise we’re into the summer, the marching season and months of paralysis.

If that happens then there is a real question over whether Stormont can survive.

There has been mention of collapsing Stormont and holding Assembly elections in tandem with the May Westminster elections. But why hold elections to more crisis?

The Stormont House Agreement entailed the British government committing grants and loan-raising powers of £2 billion to allow the Northern Executive to cushion the effects of welfare reform, start a major public sector redundancy scheme, deal with the past, support shared and integrated education, and more besides.

In addition, the North was to get corporation tax-setting powers by May.

But all that hinged on the welfare deal. So, if the deal is reneged on, some, most or all of those plans and commitments will be abandoned. Welfare recipients certainly will be worse off then.

In terms of all-island politics, this also raises the question of when is a deal a deal. Gerry Adams and Martin McGuinness signed up to the Stormont House Agreement, but now seem to be saying they didn't quite realise what they were endorsing, or that they were somehow bamboozled in the negotiations.

Negotiating reputation

That doesn’t reflect well on them, particularly giving their reputation as the sharpest of negotiators.

All this has dulled some of the gloss of the party’s very successful weekend ardfheis, although the bulk of its supporters will keep the faith no matter what the leadership does.

Sinn Féin's opponents in Leinster House certainly will try to exploit this debacle by querying whether the party's word can be trusted: were they to enter Government in the South would they honour agreements, or when the going got tough would they seek to resile from them?

Needless to say, several unionists and some other politicians at Stormont were keen to suggest this crisis was really precipitated by Sinn Féin being spooked by charges that it opposed austerity in the South but supported it in the North - that it was all about getting Sinn Féin into government in the Republic, regardless of what instability was created North of the Border.

Equally, they weren’t slow in suggesting that this logjam could also serve as a distraction to the latest sex abuse allegations implicating the republican movement.