The DUP has said it aims to secure at least a 40 per cent No vote in the forthcoming referendum.
The Rev Ian Paisley, the Democratic Unionist leader, said the assertion by the Ulster Unionist leader, Mr David Trimble, that 60 per cent support was necessary showed there was "everything to play for".
Writing in yesterday's Belfast Telegraph, Dr Paisley said he was not anti-peace and would support the deal if he thought it could guarantee an end to violence in the North. But the agreement could not bring peace and the RUC Chief Constable, Mr Ronnie Flanagan, had said that republican violence would continue, he said.
The DUP calculates that 56 per cent of unionists - a combination of dissident UUP members, the UK Unionist Party and the DUP - are opposed to the deal. "I am convinced that the No vote can secure more unionists than the Yes vote," Dr Paisley said.
"Those who intend to vote No, and especially those who as yet are undecided, should take heart that there is everything to play for. Indeed, the suggestion by David Trimble that only a Yes vote registering 60 per cent will suffice is all the more reason why the No vote has more than a chance of making its mark."
The DUP leader accused supporters of the peace deal of black propaganda. "We have seen the scare stories used against those of us who are advocating a No vote. It is claimed there is either `compromise or conflict' to chose from, that a No vote is a vote for war, while a Yes vote is a vote for peace. These claims must be answered.
"Hundreds of thousands of ordinary decent Ulster people resent that insinuation. A No vote is the only positive way you and I can declare our faith in the truth, real justice and meaningful and lasting peace, while at the same time saving the Union.
"A Yes vote is a vindication of terrorism, not a reprimand for violence. Given that the government has rewarded terrorism, I would suggest that there is little chance of terrorists giving up the means that secured for them so much!"
Dr Paisley predicted that "scurrilous and outlandish attacks" would be made against him, his party, and other unionists who opposed the agreement. Unionist voters should not be distracted from the "flaws" of the deal, he said. "This is not an agreement to secure the Union at all but an agreement with Gerry Adams to wreck the Union."
Senior Ulster Unionist officials yesterday met to discuss party strategy for the referendum campaign but no details of the outcome of the meeting were available.
Meanwhile, Mr Sean Farren of the SDLP yesterday denied claims by Sinn Fein's vice-president, Mr Pat Doherty, that the SDLP had "bottled out" at the Stormont talks. Accusing Sinn Fein of a "deliberate misinformation campaign", he said: "There is absolutely no truth in the claim that the SDLP failed in its obligations with respect to any issue in the negotiations. Not only had the SDLP detailed position papers on all of the issues but it negotiated on all strands.
"Sinn Fein's approach was, by contrast, selective. On Strand One, Sinn Fein only published proposals in the very last week of the negotiations and these proposals borrowed heavily on ideas already well advanced by the SDLP," he said.
The UK Unionist leader, Mr Robert McCartney, last night said the agreement will guarantee more violence in the North. Mr McCartney, who was addressing a No rally in Lisbellaw, Co Fermanagh, said: "There is no historical record of those who have used political violence successfully ceasing to use it until either they succeed in their political objectives or the forces of democracy rise up to defeat them."
The Workers' Party yesterday called for a Yes vote in the forthcoming referendum. "This agreement provides a fresh opportunity for all the people of Northern Ireland to build a peaceful and democratic future together," a spokesman said.