Theresa May might not be able to deliver a Brexit agreement at all, according to the Labour leader.
Brendan Howlin says the confusion over the weekend in the British cabinet raises questions over their ability to reach a final deal.
The British Prime Minister gave assurances in the House of Commons yesterday that the deal reached on Friday will stand.
But Brendan Howlin has his doubts.
He said: "The basis of any negotiation is that you trust the people across the table.
"If you believe the people across the table can't actually deliver what is negotiated, well then you have no basis for negotiation.
"I think there is real doubt now whether Theresa May and her current government, divided as they are on this crutial issue, can actually deliver on a final settlement."