Former Northern Ireland secretary Lord Hain is set to accuse the government of playing a dangerous game with the peace process over its handling of Brexit and the border.
The House of Lords is due to debate a report on Brexit later on Tuesday.
Lord Hain is expected to address the UK's recent proposals for the border.
He is to say they are "long on good intentions and aspiration, but breath-takingly short on practical detail as to how it will work after Brexit".
The former Labour secretary of state will say the idea that 80% of cross-border trade can simply be waved through is "pie-in-the-sky fantasy".
Lord Hain will also argue that the UK government appears to be telling the EU that "as part of the divorce settlement", it can do what it likes with the Irish border and "if that means a 'hard' border then that will be the EU's fault and not ours".
He will also criticise what he regards as the government's "dogmatic insistence on taking Britain out of the jurisdiction of the European Court of Justice", which he thinks could put vital European peace funding at risk.
Speaking to BBC Northern Ireland's Good Morning Ulster programme on Tuesday, Lord Hain said Northern Ireland should be part of the customs union and single market post Brexit.
"The whole of the UK, in my view, should be in the customs union and single market," he said, "But if the government flatly rejects that, as it has done so far, at least Northern Ireland should be."
He described the government's current proposals as laid out in the recent paper as "delusional, contradictory and potentially very damaging".
He added: "The Irish border has become part of a bargaining chip in what looks increasingly like a hard right Brexit with no soft landing, just falling out of the EU, it seems to me. with catastrophic consequences.
"This ought to be resolved by a common engagement and finding practical answers."
Lord Hain also believes ministers' "worthy aim of saying the UK should remain part of the PEACE Programme" cannot be squared with the UK's policy of leaving the jurisdiction of the European Court of Justice.
Lord Trimble, who is also due to take part in the debate later, dismissed Lord Hain's words saying he was "flying kites".
"Lord Hain would prefer Northern Ireland to be part of the European Union but the people have decided otherwise, he has to get his head around that," he said.
Lord Hain's call for Northern Ireland to be in the same single market and customs union as the Republic of Ireland was not possible, he added.
"It is not in our interests. It runs counter to where the balance of our trade is and how our economy is organised. We are part of the UK, that is where the bulk of the goods manufactured in Northern Ireland go".
He said: "If you really want to have an easy solution, then you have no tariffs, that would be the ideal situation. Then we would be able to continue in the way that we have done over the last decades, but we have not anything in any way encouraging from the EU."
Lord Trimble said Brussels was causing the problems.