BRUSSELS (Reuters) - The European Union told Britain to rework its Irish backstop proposal by Friday but feared it would struggle to secure a deal that satisfied pro-Brexit lawmakers before a key vote in the UK parliament on Wednesday.

FILE PHOTO: Britain's Attorney General Geoffrey Cox is seen outside of Downing Street in London, Britain, February 27, 2019. REUTERS/Peter Nicholls/File Photo

Just 22 days before Britain is due to leave the EU the two sides are locked in a game of brinkmanship and attempts to reach a mutually acceptable deal could go down to the wire.

EU diplomats briefed on the negotiations said the UK’s top lawyer Geoffrey Cox had proposed a disputes arbitration panel that would not be obliged to refer cases to the EU’s top court, the ECJ, whose jurisdiction Britain wants to leave.

“We are now in a state when we are discussing proposals we have rejected months ago,” an EU diplomat said. “They’ve sent in a criminal lawyer who doesn’t know EU law or customs rules. We are explaining from scratch why his ideas won’t fly.”

May tasked attorney general Cox with securing concessions from the EU on a key demand of pro-Brexit lawmakers, namely that divorce provisions to ensure no hard border on the island of Ireland would not trap the UK in the bloc’s trade rules.

EU negotiators object that the Cox proposal would unpick the Withdrawal Agreement reached by the EU and UK last year after months of tortuous negotiations.

Britain’s parliament rejected that pact, largely over concerns over the backstop. The bloc has offered addendums and extra assurances on the text to make it more palatable but refuses to change its substance.

While the EU still hopes for a breakthrough at the weekend, Brussels fears British Prime Minister Theresa May could try to negotiate directly with the other 27 EU leaders at a Brussels summit on March 21-22, just a week before Brexit day.

WEEKEND BREAKTHROUGH?

According to EU diplomats, Cox’s backstop solution involved an arbitration panel that would decide if enough “good faith” and “best endeavours” were being shown negotiating a post-Brexit trade deal.

The panel could rule positive even in the absence of a final trade agreement or alternative solutions to maintain the open border between EU member Ireland and the British-ruled province of Northern Ireland. It will be the only land border between the UK and the bloc after Brexit.

In such a scenario, the EU and the UK would fall back to a “mini-backstop” which would include fewer checks than envisaged in the Withdrawal Agreement, the sources said.

A second EU diplomat said that would only cover checks for animal health, food safety and prohibited items. It would not cover production standards or where the goods originate which are essential to protecting the EU single market.

Other diplomats said Cox’s proposal lacked detail and that the EU would not agree to replace the backstop with arrangements that failed to specify exactly how the Irish border would be kept open.

In the event of a breakthrough, May would be expected in Brussels on Monday to seal the deal with Jean-Claude Juncker, the head of the bloc’s executive.

However, many EU diplomats are sceptical an agreement can be reached in time for a March 12 vote in the House of Commons on May’s plan to leave the bloc.

“Now I’m sure it’ll go down to the wire at the summit,” a third EU diplomat said on condition of anonymity.

The bloc expects May to ask her peer leaders for an extension to the current departure date of March 29 should both sides fail to bridge their differences, in order to prevent a no-deal Brexit that many say could cause economic turmoil.

A short extension until mid-May or the end of June is acceptable to the other 27 EU states, even if many doubt a delay will help break the impasse.

“It’s just postponing the cliff-edge. At least it gives us more time to prepare for no-deal disruptions,” said a fourth diplomat dealing with Brexit in the EU’s political hub Brussels.