THE European Union has rejected UK attempts to force concessions on the Brexit deal, and last night simply re-offered a proposal the UK has already turned down.

Chief negotiator Michel Barnier said the UK could have a unilateral right to leave the customs union but stressed, however, that Britain would still need to honour its commitment to preserve a border free of controls between the Republic of Ireland and Northern Ireland.

This would effectively create a border in the Irish Sea if the UK chose to withdraw – a plan which has previously been rejected by May as something “no Prime Minister would agree to”.

READ MORE: Brussels would be blamed if Brexit ends badly, Jeremy Hunt claims

The original EU proposal was vehemently opposed by the DUP over a year ago.

And last night, the Brexit Secretary Steve Baker dismissed the move as old news.

“With a very real deadline looming, now is not the time to rerun old arguments,” he tweeted. “The UK has put forward clear new proposals. We now need to agree a balanced solution that can work for both sides.”

Just three weeks before Britain is due to leave the EU on March 29, the divided UK Parliament has yet to approve the EU-UK Brexit deal which looks set to be rejected by MPs.

Earlier, Theresa May issued a plea for support as the showdown looms, warning the UK will be plunged into crisis if the Withdrawal Agreement is voted down.

In a stark message ahead of Tuesday’s Commons vote, the Prime Minister said “no-one knows” what will happen if her plan is defeated, with the possibility of Brexit being derailed completely.

May said both the democratic and economic cases for backing her deal are “clear”, and issued a plea to MPs: “Let’s get it done.”

The Prime Minister used her speech in Grimsby to urge the European Union to give ground on the Northern Ireland backstop and call on Tory Eurosceptics to recognise that failure to back the deal could result in a softer Brexit or another referendum.

“Next week, MPs in Westminster face a crucial choice: whether to back the Brexit deal or to reject it,” she said. “Back it and the UK will leave the European Union. Reject it and no-one knows what will happen.

“We may not leave the EU for many months, we may leave without the protections that the deal provides. We may never leave at all.”

READ MORE: Nicola Sturgeon had the best response to a line in Theresa May’s speech

The SNP demanded Theresa May stop blaming others for the crisis, and start taking personal responsibility for the current situation.

Ian Blackford MP said the proposed deal was fundamentally flawed and would be devastating for jobs, living standards and the economy.

He said: “Theresa May must stop passing the buck and take personal responsibility for the Brexit crisis created as a result of her own intransigence.

“With three weeks to go until the UK is due to crash out of the EU, it is vital that MPs reject May’s bad deal, extend Article 50, and hold a second referendum on EU membership.

“Whatever happens now, it is increasingly clear that the best way to properly protect Scotland’s interests is with independence.”