The Rev Ian Paisley has called for a full re-negotiation of the Belfast Agreement.
The anti-Agreement Democratic Unionist Party leader's call came after Ulster Unionist leader David Trimble proposed that there should be a "formal review " of the deal unless the current impasse over IRA decommissioning, policing and demilitarisation was ended.
Mr Paisley said what was needed was not a review but full re-negotiation of the entire Agreement.
He said Mr Trimble had in effect now "surrendered to what we have always been saying - that there is no way forward except by renegotiating and getting a proper democratic structure".
Mr Trimble yesterday gave a gloomy assessment of the chances of a breakthrough in the current stalemate during a visit to Washington.
He said: "I think the obvious thing to look towards is that if progress isn't achieved in the current talks - and I've no reason to believe it will be - then we need to move towards a formal review of the Agreement with the purpose of devising and sustaining workable democratic structures."
Such a review would mean suspending devolution in the province for the second time.
Mr Paisley told the BBC Radio Ulster programme Inside Politicsthat Mr Trimble was now admitting that the DUP and majority of unionists had been right about the Belfast Agreement all along.
"He told us this was the only alternative we could have, now he says we have to devise new democratic structures," he said.
Devising new structures meant "throwing away" the Agreement, Mr Paisley said, adding: "We have been pressing Tony Blair and the opposition that what we need to have a complete renegotiation, something different."
The DUP leader said his party would take part in the negotiations, but with the Government, not with Sinn Fein.
"Those that front an armed organisation who have committed terror and mayhem in this province, have no place in the democratic structure, no way will we be sitting down with IRA/Sinn Fein," he said.
Mr Paisley also condemned RUC Chief Constable Sir Ronnie Flanagan for talking to the nationalist SDLP about the future of policing while not having discussions with his own party.
He said he repudiated the right of any Chief Constable "outside the elected leadership of the of the people of Northern Ireland, to negotiate with one sectional interest in order to sell the police force out to them".
Meanwhile, following the re-selection of anti-Agreement MP the Rev Martin Smyth as UUP candidate for South Belfast, it looked likely that the pro-Agreement Progressive Unionist Party would stand against him.
PUP Assemblyman David Ervine said the party was "very likely" to put a candidate up to give pro-agreement unionists in the constituency someone to vote for.
Mr Smyth has held the seat since 1982, and had a 5,000 majority at the last election.
On Friday night he beat off a challenge for the constituency nomination from pro-Agreement Michael McGimpsey, minister for the Arts, Culture and Sports in the Stormont Executive.