DUP deputy leader Mr Peter Robinson has said the Ulster Unionists' days of leadership are over and the party will be heavily punished at the next Assembly elections.
Addressing his party's annual conference, he spoke of the UUP's "ineffective voice and incompetent team". They had shown their true worth by negotiating the "failed" Belfast Agreement and allowing "terrorists" into government.
"Their record shows they are cheats and frauds, deceivers, pretenders and imposters," he added. For the last 30 years, the UUP had dominated unionism.
But those days were over. The UUP would "get from the unionist electorate what they deserve". The unionist people have waited long enough, he said: "They want change and change is what they will get."
If the DUP won a majority of unionist seats in the Assembly, Mr David Trimble could not be re-elected First Minister. The DUP would force a renegotiation of the entire agreement. Assembly elections are scheduled for next May and Mr Robinson said his party would challenge any attempt to postpone them.
"I warn the government that if it seeks to extend the life of the Assembly, it will have no democratic authority, no mandate and no legitimacy. Suspending the Assembly is one thing. Suspending democracy is quite another." The current political talks at Stormont were worthless as real negotiations could not take place until after an election, he said.
"The people have a right to an election and the politicians need a fresh mandate. Yesterday's men cannot deliver.
"Cobble it together now if you can, but you will still have to do it properly after an election. We will not be bound by the concessions Trimble will make." Mr Robinson also predicted that attempts to revive the agreement would fail.
"Not since Frankenstein's creation has so much effort been invested in resuscitating such a grotesque monster," he stated. He accused the British government and "its lackeys in the pro-agreement parties" of spending "their every waking moment demonizing this party".
All the resources of the state were used against the DUP and the media "acted as accomplices".
"We have taken on Sinn Féin/IRA. We have harried the Ulster Unionists. We have exposed the agreement's folly to public ridicule and we have brought the process to the point where change represents the only way forward. The Prime Minister says this is not an agreement which should not be set aside lightly. He is right - it should be tossed away with great force."
Meanwhile, the Rev Ian Paisley warned that any DUP member caught making contact with Sinn Féin would be expelled from the party.
He insisted that while the DUP was pro-devolution, it would not enter government with parties which had paramilitary links.
"Decommission of terrorist weapons must take place before the bar to any cabinet position could be considered to be lifted," he said.
Dr Paisley also warned Mr Blair not to try and "push the agreement down the throats of true democrats who are not prepared to bend the knee to the insatiable demands of Sinn Féin/IRA".
There was an alternative to the agreement and future political negotiations had to be built on "a truly democratic agenda", he added.