Sinn Fein will not be badgered on the policing issue, senior spokesman Gerry Kelly has told his party's annual conference in Dublin.
Gerry Adams and Martin McGuinness at the Sinn Fein conference
Mr Kelly said the party would not be forced into accepting "anything less than a new beginning to policing".
He said the main issue was the transfer of powers from London to a restored assembly and all-Ireland institutions.
Mr Kelly warned delegates the issue "could not be dusted down and put on the shelf until a united Ireland".
Earlier, chief negotiator Martin McGuinness said the future of the Good Friday Agreement "was on the line".
However, he said republicans should not be worried because, even if the agreement fell, its substance "had been secured as the minimal threshold for anything that might replace or supersede it".
The DUP's Nigel Dodds accused Sinn Fein of "gross hypocrisy" after the conference.
"On the one hand Sinn Fein leaders are jumping up and down demanding that the government apply pressure to the DUP to admit the republican movement into government despite the ongoing criminality, racketeering, and the retention of illegal terrorist arms.
"On the other hand they state they will not be badgered into support for the police and maintain a policy of rejectionism," he said.
On Saturday, Sinn Fein leader Gerry Adams told the conference there could be no dilution of the Good Friday Agreement.
He added that Sinn Fein's engagement with unionism must deepen.
The months ahead were crucial, he said, and he had huge reservations over the way the governments were approaching talks aimed at restoring devolution.
Mr Adams poured cold water both on the idea of a two-stage return of local government and on British-appointed commissioners running Northern Ireland.
The Sinn Fein leader welcomed the IRA's move to formally end its campaign and said no one should harbour the illusion that the republican struggle could be advanced any further by an armed campaign.
The future, he said lay solely in politics.
"Undoubtedly there are some who believe that the IRA has made a mistake.
"They are entitled to their opinion but to no more than that," he said.
But the Sinn Fein leader said Ian Paisley and the DUP also faced challenges.
Are they ready to build a shared future and "is their war over", he asked.
Mr Adams said Sinn Fein would be in government in Northern Ireland and would, depending on its mandate, consider being in coalition in the Republic.
"We will never meekly serve our time. Our objective is an all-Ireland parliament for all of the people of Ireland," he said.
More than 1,000 party delegates from the north and south of Ireland debated almost 500 motions at the party's three-day conference in Dublin's Royal Dublin Society hall.