Tonight in Carryduff, on the outskirts of south Belfast, hundreds of unionist hardliners will gather for a protest rally against the Stormont talks which they believe are a sell-out to nationalists.
The DUP deputy leader, Mr Peter Robinson, and the UK Unionist leader, Mr Bob McCartney, will address the crowd. They are expected to make stirring denunciations of the peace process and of the Ulster Unionist leader, Mr David Trimble.
Both parties have accused him of a U-turn on entering negotiations with Sinn Fein and of betrayal in joining a process which they insist will eventually destroy the Union.
The views of Mr McCartney and Mr Robinson are already well-known. But it is the identity of the third speaker which is causing considerable unease in UUP circles. Mr Nelson McCausland, a UUP councillor and High Sheriff of Belfast, was once a close associate of his party leader.
He was one of Mr Trimble's more prominent campaigners in the UUP leadership contest two years ago and was tipped to be the next MP for North Belfast.
Mr McCausland's decision to share a platform with the UUP's rivals has been interpreted as an endorsement of their position on the talks. He is not the only UUP representative sympathetic to the Paisley-McCartney line. Another leading figure in east Belfast, who had also campaigned for Mr Trimble, helped organise the huge anti-talks rally in the Ulster Hall last month.
Several middle-ranking UUP activists, including a councillor, attended the event. There were calls of "traitor" and "Lundy" from the crowd whenever Mr Trimble's name was mentioned. But despite these insults, the DUP and UK Unionists are anxious not to alienate UUP grassroots.
"There are many good, decent people in the UUP who are deeply disturbed about the direction in which their leadership is heading," says the DUP secretary, Mr Nigel Dodds.
The DUP has little choice but to court UUP grassroots. The campaign against the 1974 Sunningdale power-sharing executive succeeded because of support from loyalist paramilitaries. But this time the UVF and the UDA are on board the talks train.
The DUP and UK Unionists must broaden their base and win support among ordinary unionists if their campaign is to succeed. Mr McCartney is particularly suited to courting UUP grassroots. "If the DUP was arguing the case alone, it would be marginalised and dismissed," says a UUP member.
But the UK Unionist leader gives the anti-talks campaign gravitas, he says. "Paisley's speech at the Ulster Hall was over-the-top - he just played to the audience's emotions. McCartney argued with logical precision and made a rational, reasonable case." Mr Dodds disputes this view of his party leader but agrees: "Bob reaches places we can't."
The DUP-UK Unionist coalition has two objectives: to pressurise the UUP to withdraw from talks; and to prepare the ground for a "no" campaign in the referendum that the British government plans to hold in Northern Ireland after the talks end in May.
Tonight's rally in Carryduff is only the beginning of the campaign of opposition. Dozens of similar events will be staged across the North in coming months. So far all the rallies have been indoors and there are no plans for street demonstrations.
The organisers say they wish to keep their protests non-confrontational but the most likely reason is that they lack the mass support they enjoyed during the campaign against the Anglo-Irish Agreement 12 years ago.
Still, the potential for the McCartney-Paisley axis to damage Mr Trimble should not be underestimated. The UUP leader's main weakness is the lack of unanimous support for his position among his nine other parliamentary colleagues.
Two MPs - Mr Willie Thompson and Mr Willie Ross - have already spoken out against negotiations with Sinn Fein. Three more - the Rev Martin Smyth, Mr Clifford Forsythe and Mr Roy Beggs - are reportedly very dubious.
Mr Trimble can rely only on the backing of two MPs - Mr Ken Maginnis and Mr Jeffrey Donaldson. His deputy, Mr John Taylor, is said to be "impossible to pin down" on the issue and the North Belfast MP, Mr Cecil Walker, appears to take a back-seat role.
Under these circumstances, a campaign by the DUP/UK Unionists against Mr Trimble's strategy, combined with a softly-softly attempt to woo his party's grassroots, could have serious repercussions.
The UUP is, however, playing down the threat. A member of the party talks team said: "There are no more divisions or disagreements in the UUP than in any other party.
"It is not the case that David Trimble is charging ahead with the bulk of the party dragging their feet behind him. Some unionists might disagree with our strategy and people like Willie Ross and Willie Thompson have made criticisms. "But they are individuals and it must be questioned how representative they are. David Trimble has unanimous endorsement from the party executive to decide our talks strategy."
However, the UUP leader has been portrayed as "running scared" by the former DUP MP for Mid-Ulster, the Rev William McCrea. "David Trimble declined an invitation to address the Ulster Hall rally, saying he had a previous engagement. Well, we are now asking him to choose a date and time to his liking for an open debate.
"We plan to hold a rally in his constituency of Upper Bann and ask him to come along and argue his case with Dr Paisley and Bob McCartney.
"A refusal would be scorned by ordinary unionists. David Trimble has time to go to the White House, he has time to go to the Labour Party conference, so he will be expected to make time for other unionist politicians."
The UUP leader's opponents believe he is on a collision course anyway and that his talks strategy is fundamentally flawed. Mr Trimble, they say, is hoping to reach an agreement with Mr John Hume that sidelines Sinn Fein.
Mr McCrea is certain that he will fail: "If David Trimble thinks that John Hume will walk away from Gerry Adams, he is living in cuckoo land."