The Democratic Unionist Party has been accused of being "arrogant" and "rudderless" over its position on Brexit.
SDLP leader Colum Eastwood said the DUP and UK Government need to "wake up to the reality" that an economic border on the island of Ireland is "unenforceable".
Mr Eastwood has urged Taoiseach Leo Varadkar not to sway from his position that there can be no new economic or physical border imposed on the island of Ireland.
Speaking ahead of his meeting with the Irish premier in Belfast on Friday, Mr Eastwood said: "An Taoiseach should not be put off by the DUP's feigned outrage over his recent comments.
"People should not confuse statements of diplomatic reality with statements of extremity. The Irish Government's position is rooted in reality - the DUP's position is rudderless."
He added that the DUP, "in their arrogance" continue to believe "that they can enforce a border on this island which would deeply damage the North's economy."
Mr Eastwood also said he will asking the Taoiseach to become more directly involved in the crisis talks at Stormont aimed at restoring powersharing.
"Establishing those institutions and a local Executive will give us a voice on Brexit and will also allow us to get on with the work of tackling the mounting problems we collectively face in health, education and in our economy," said Mr Eastwood.