SINN Féin and the SDLP have called on the DUP to reconsider its opposition to a Brexit border deal, insisting it is in the best interests of the north.
Sinn Féin deputy leader Mary Lou McDonald said the region should remain within the customs union and single market, in line with its referendum vote.
The Dublin TD, tipped as the next leader of the party, said: "That is the only guarantee of stability and certainty that will deliver the full protection of the Good Friday Agreement in all its parts; including Irish citizenship and therefore the benefits of EU citizenship.
"This is a common sense, practical, and achievable proposal and, despite the claims of the DUP, it will not change the constitutional position of the north."
SDLP leader Colum Eastwood, who had earlier described the expected deal as "a big win", also urged the DUP to "act in Northern Ireland's interest".
"Reports that the UK could concede the principle that there must be 'continued regulatory alignment' with the rules of the single market and the customs union across Ireland, particularly in areas of north/south cooperation, is a positive move," he said.
"All steps must be taken to protect the north's economy, our political progress and the terms of the Good Friday Agreement.
"That has long been the position of the European Union. It is welcome that the British government now seems to be accepting that position."
Alliance MLA Stephen Farry also said it was "really encouraged" by the speculated deal which he described as "entirely in line with the principle of consent and devolution".
"This is about recognising the interdependent nature of the economy on the island of Ireland but also with the rest of the UK. This is not an either/or choice. Rather it allows Northern Ireland to be a bridge to both Europe and the rest of the UK. This could be a massive opportunity - a real economic game-changer for us," he said.
