Stephen Barclay said the UK should be given another year to find a new policy for the Northern Ireland border.
The intervention comes as Downing Street said it would not be bound by an “artificial deadline” in talks.
“We are told the UK must provide legally operative text by the 31 October,” the cabinet minister Mr Barclay said in a speech in Madrid on Thursday.
“Yet the alternative to the backstop is not necessary until the end of the implementation period in December 2020.
“And this will be shaped by the future relationship – which is still to be determined.
“In short why risk crystallising an undesirable result this November, when both sides can work together – until December 2020.
“In summary, the EU risks continuing to insist on a test that the UK cannot meet and that the UK parliament has rejected three times.”
The plea for more time was made after Emmanuel Macron and the Finnish presidency of the EU issued an ultimatum in Paris on Wednesday, giving Boris Johnson until the end of September to table workable proposals – or “it’s over”.
The UK is yet to meet EU requests to propose a concrete alternative to the Irish backstop, which Mr Johnson says must be scrapped. EU officials fear they may be “led up the garden path” by British negotiators, who had been visiting the EU capital frequently for talks, but with little sign of actual progress.
The admission is an about-face by the British government. Speaking alongside Angela Merkel in Berlin last month, Mr Johnson said he was “more than happy” with the “blistering timetable” of finding a replacement for the backstop within 30 days.
A European Commission spokesperson on Thursday afternoon confirmed the UK had sent “some documents” to Brussels ahead of a visit by Mr Barclay to meeting with Michel Barnier, the bloc’s chief negotiator, on Friday.
But a UK government spokesperson confirmed that the papers were not a concrete written proposal, telling reporters: “We have been having detailed discussions with the Commission’s taskforce 50 [negotiating team] in recent weeks. We have now shared in written form a series of confidential technical non-papers which reflect the ideas the UK has been putting forward.
“We will table formal written solutions when we are ready, not according to an artificial deadline, and when the EU is clear that it will engage constructively on them as a replacement to the backstop.”
The December 2020 date named by Mr Barclay is the end of the transition period negotiated by Theresa May. The EU has consistently said that if the withdrawal agreement is not approved, there cannot be a transition period – and that without a Northern Ireland backstop, there cannot be a withdrawal agreement.
Mr Barclay’s latest statement is essentially a request for the EU to drop any demand for a backstop in the withdrawal agreement, and let the UK have a transition period without a backstop in place.
The transition period can be extended by another two years beyond December 2020 with the agreement of both the EU and UK, though the prime minister said earlier this week he had no “intention” to do so.
A European Commission spokesperson told reporters in Brussels on Thursday: “What I can confirm is that we have received documents from the UK. On this basis we will have technical discussions today and tomorrow on some aspects of customs, manufactured goods, and sanitary and phytosanitary rules.
“Then the discussions will also take place at political level because Michel Barnier, the commission’s chief negotiator, will meet Steve Barclay tomorrow, on Friday.”
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