Boris Johnson has warned people not to “hold their breath” for a Brexit breakthrough.
His comments come despite claiming the “mood music” on his visits to Germany and France was “very good”.
He said: “They could see that we want a deal, they can see the problems with the Backstop.
“Clearly, Angela Merkel thinks that the solutions can be found within 30 days – actually what she meant was if you can do it in two years, you can certainly do it in 30 days.
“But I want to caution everybody, OK, because this is not going to be a cinch, this is not going to be easy.
“We will have to work very hard to get this thing done.”
Mrs Merkel had piled pressure on him to find a workable solution to the Backstop – and he insisted there were “lots of ways” to achieve frictionless trade at the border in Northern Ireland.
But the PM pleaded: “To persuade our EU friends and partners, who are very, very, very hard over against it, will take some time.
“I’m afraid we will have to prepare to come out without an agreement and we can do that, we are very confident that we will be OK because we will have all sorts of preparations in place.”
He added: “We are making progress but I am just telling people not to hold their breath, because I have seen the way these Brussels negotiations work.”