The SDLP is accusing the DUP of endangering the fundamental principles of the Good Friday Agreement.
The party says it will stand firm against any concessions to DUP demands.
The SDLP is also criticising a recent British government list of what the Agreement's fundamentals are, and upon which the DUP have based their proposals.
The SDLP has slammed DUP demands, such as the right of 30 assembly members to over-rule any ministerial decisions, and the power of the assembly to veto rulings by the North-South Ministerial Council.
The party has pointed to the DUP’s poor record for powersharing with nationalists on local councils and asks why they should be trusted to govern fairly if the Agreement’s checks and balances are overturned.
The SDLP leader, Mark Durkin, rebutted claims by the DUP that its proposals are consistent with the fundamentals of the Agreement.