Sinn Féin have turned down an invite to talk to Arlene Foster about a cash for ash inquiry.
The North's First Minister has offered her colleagues a last-ditch chance to save their power-sharing deal.
But she is being blamed for the energy scandal causing the current unrest and Sinn Féin say they will not be happy until she steps down.
The resignation of Martin McGuinness earlier this week has been seen as an attempt to force Ms Foster out.
The party's Deputy leader Mary Lou McDonald says they have tried every other option: "Far from running away from it, we have dealt with this head on.
"Large numbers of Sinn Feiners spent their entire Christmas dealing with this issue, privately, publically.
"We now have a last minute attempt from the DUP to cobble something together."