The Unionist representatives are already pledged to oppose plans for innovations, such as crossborder bodies. The British and Irish governments argue that such institutions are necessary to give tangible expression to the Irishness of a large section of the population. The Unionists say such things are against their interests and would set them on a "slippery slope" to a united Ireland. Both leading Unionist parties had pledged they will not discuss the framework document with the Government.
This course of action will not derail the peace process: both the IRA and loyalist ceasefires look fairly secure, and political activity will continue with or without the Unionists. But a blow will be struck against the ideas of an inclusive peace process if the representatives of the larger part of the population opt out of participation.
That will come about if the Unionist community as a whole endorses the hard line of its MPs and concludes that the framework document represents a bridge too far. But will it?
Unionist MPs are more known for their representational skills than qualities of leadership, and in the past have generally stayed in tune with their community. But this time there are real grounds for thinking, as the Government hopes, that a gap exists between the MPs and their grassroots.
The IRA cessation of violence happened fewer than six months ago, yet already the atmosphere has been greatly changed. The original caution that greeted the ceasefire developed into relief and then - with classic Northern Irish inhibition - a sort of suppressed near-euphoria.
Nearly six months on, there has still been no dancing in the streets and no exuberant display of celebration. There is still anxiety that something could go wrong, and still less than complete confidence that the violence has gone for good.
But there is also, in many quarters, a deep appreciation of the benefits of peace, and the desire to maintain it is palpable and fervent. The prevailing belief is that the ceasefires are for real and that an unprecedented opportunity now exists for a new start.
To date, little or none of this has been reflected by Unionist MPs, some of whom can be heard arguing that the cessation is a temporary tactical manoeuvre and that this is a time for standing fast. A small segment of Unionist opinion shares this view, but many more Protestants seem to believe that this is a time of opportunities rather than peril.
This is not to say that Unionists have jettisoned all their traditional beliefs and suddenly decided to approve movement towards a united Ireland; they have not. They are as anxious as ever to maintain the union and as worried as ever about the type of crossborder bodies envisaged in the framework document.
But those traditional political aims now co-exist with the desire to maintain the peace. There is thus a strong new element in the Unionist mindset.
The question is whether this will disrupt the former patterns or whether old habits will reassert themselves. In the past, Unionists have often opposed British initiatives, sometimes successfully. In 1974, when the Heath government introduced new arrangements along similar lines to the framework document's ideas, a Protestant general strike brought the country to a standstill and led to its abandonment.
Protestant objections to the 1985 Anglo-Irish agreement were just as intense, but the Loyalist campaign against it, though protracted, was disorganised and eventually ignominiously fizzled out. None the less, the thought has continued to lurk in the Unionist psyche that the force of Protestant numbers can, if properly mobilised, thwart the wishes of British governments.
If the framework document were to be introduced at a time of continuing killing and armed conflict, the probability is that a coordinated Unionist campaign would emerge with the aim of sabotaging its all-Ireland dimensions.
This time round, however, there are grounds for believing that Protestant reactions may be more thoughtful and considered. The key Unionist parties have already committed themselves to outright rejection, but the once- violent loyalist paramilitary groups are now displaying much more open minds. In place of the standard dire threat, they are now appealing for calm.
Much of the Unionist business community is surprisingly pragmatic about innovative north-south links, and even prepared to consider whether they might bring new openings for trade. And above all there is that new constraint: the sense that nothing should be done to jeopardise the peace.
Yesterday one Protestant clergyman said: "They're hoping against hope that it will hold. People are just quietly waiting. They're holding their breath and there's quite an edgy mood. A lot depends on how the politicians play it."
His comments reflected the importance of presentation and micro-management in the way that something as vital as the framework document is presented to a community that is so nervous of innovation and so prone to volatility. A couple of ill-considered ministerial comments could spell disaster.
Six months ago the IRA faced its moment of truth, gauging whether to continue with terrorism or to pursue its aims by peaceful means. Gerry Adams and the other Republican leaders opted for politics and, in the short time since then, have already built many new political relationships.
The framework document looks like becoming the foundation of a consensus on how to proceed, and will form the basis of the approaches of the two governments, the Clinton administration, Irish America and the European community.
People in the Unionist community privately admit, in a way their MPs do not say publicly, that a purely negative reaction to the document would mean consigning themselves to a new phase of isolation - which would be both uncomfortable and unproductive, and which would cast a shadow on the prospects for lasting peace.
Going down that road would lead to confrontation with the Government and all those other forces, and would lead to Unionism being accused, fairly or unfairly, of being against peace. The Unionist MPs have yet to explain how their community would gain from such an approach: they might help to bring down the Government, but there is little prospect that the next British government would be any more disposed to their view.
This is a real moment of truth for the Protestant community. Its MPs have already set their face against a new beginning, but the Government's hope is that this time Unionist leaders will be told, by their own grassroots, that the time has finally come to begin working towards a new political settlement to protect the prize of peace.