Reuters
Speaking at his first press conference since being appointed to lead negotiations, Barnier said there would be "some use in a transitional period" if it "eased the path" towards a new relationship between the UK and the 27 European member states, but insisted the UK would not be allowed to "cherry-pick" the best deal for itself.
That is significant: a transitional deal could well end up meaning that the UK keeps freedom of movement for several years after it triggers Article 50, something that would be received badly by those keen on placing immediate curbs on immigration.
The point of a transitional deal would likely be to keep some single market access while the UK strikes up new trade deals on the continent and other parts of the world. As Buzzfeed's Alberto Nardelli reports, many EU leaders appear unwilling to give the UK a transitional deal which gives the UK generous single market access while also placing curbs on freedom of movement.
The government's position on a transitional deal remains unclear. Asked about Barnier's comments this morning, Downing Street all but ruled out a transition deal. "We will trigger Article 50 no later than March this year," the prime minister's spokesman said.
"There is then a two year time frame on that process. We have been clear that we are not seeking to extend that process ... we don't want to extend it beyond the two years."
However, when asked by Business Insider whether this meant the PM had completely ruled out a transitional deal, he replied that: "We are not making any kind of commitments in that regard. We are simply going into these negotiations to get the best possible deal."
Barnier emphasised that it was "difficult to talk about a transitional period" until the European Council knew what the UK decided "intentions or requests" are, and how much access to the single market it seeks.
"The term 'transitional period' only makes sense if it prepares the way for a future relationship," he said. He mentioned options including the 'Norway model,' whereby the country pays into the EU in return for single-market access but must accept freedom of movement in return.
Asked whether he anticipated a 'hard' or a 'soft' Brexit for the UK, Barnier responded that he did not know what the terms meant.
"Frankly I do not know what a hard or soft Brexit are. I can say what a Brexit is: clear, ordered, and we will work within the council's guidelines on the content of the negotiation. We want a clear agreement, we want to reach this agreement within the limited time that we have available," he said.
Barnier also said that he expects Brexit negotiations to be complete by October 2018, eighteen months after Theresa May intends to trigger Article 50. The clause gives the UK two years to complete a formal exit, but Barnier said six months would be needed to ratify any arrangements.