Northern Ireland’s Democratic Unionist party, which props up Theresa May’s minority government, has ramped up tension in the final phase of Brexit talks by threatening to vote against this month’s Budget if she breaches its “red lines”.
The party said any post-Brexit customs or regulatory border in the Irish Sea would be unacceptable and that it would scupper the October 29 Budget in retaliation, possibly bringing down the prime minister.
It set out its position as Michel Barnier, the EU’s chief negotiator, gave his most detailed explanation yet of how border checks would work under the bloc’s plans for a Brexit deal.
A senior DUP figure told the Financial Times: “It is unacceptable that we would be treated differently to the rest of the UK. We will not be bounced into anything. If Theresa May doesn’t take our concerns on board, she may not be the leader to take us through Brexit.”
Mrs May depends on 10 Northern Ireland unionist MPs to stay in power; the DUP signed a “confidence and supply” deal in 2017, where it agreed to back Mrs May in confidence votes, votes on the Budget and on Brexit legislation.
The agreement, facilitated by the Conservatives promising an extra £1bn of investment in the region, gave Mrs May a working Commons majority of just 13. That majority would evaporate if the DUP withdrew its support.
Any DUP move to vote against the Budget would be seen as a vote of no-confidence in the government and signal the end of their deal with the Conservatives.
However, a spokesperson for Mrs May insisted that under the fixed-term parliament act losing a Budget vote was not tantamount to losing a vote of no-confidence.
The party’s new hard line followed a visit by Arlene Foster, the party’s leader, to Brussels where UK and EU negotiators are working intensively to solve the question of the “Irish backstop” — a guarantee by both sides to avoid a return to a hard border.
Britain will accept the EU’s proposal that Northern Ireland remains aligned to the single market — in the event of no final trade deal being in place — introducing a regulatory border in the Irish Sea between the region and mainland Britain. However, any checks on manufactured goods crossing from Britain to Northern Ireland could breach the DUP red line.
In turn, Mr Barnier has vowed to keep checks in a backstop to a bare minimum.
In a speech on Wednesday, he said this would mean using existing transit procedures for customs so that “the only visible and systematic checks between Northern Ireland and the rest of UK would involve scanning the bar codes on the lorries and containers”, which could be done in ferries and transit ports.
He added that similar procedures existed between the Canary Islands and mainland Spain.
Regulatory checks on industrial goods could also take place away from the border, in the market or at company premises. Food safety checks would need to happen at the border, Mr Barnier said, but he said that this could be done by making existing procedures more systematic.
However, Britain and the EU remain at odds over whether Northern Ireland should remain in the bloc’s custom union as part of the backstop, as Mr Barnier has proposed.
Mrs May’s counter-proposal is for the backstop to include a temporary customs deal covering the whole UK, ensuring that there is no customs border in the Irish Sea.
The prime minister’s team remains privately confident it can win over the DUP by producing a political declaration that states that any backstop deal would be “temporary and time limited”, pending agreement of a wider EU/UK free trade deal.
Indeed, the DUP’s threats to Mrs May could strengthen her hand in the final stages of talks in Brussels, allowing her to show the rest of the EU that she is taking risks with the survival of her government to secure a deal.
Mrs May told the House of Commons she was confident of getting a deal in Brussels and appealed to MPs from all parties to back her.
She hopes an outline agreement on the Brexit withdrawal treaty — including the Irish backstop — can be agreed at the weekend and then be put to the cabinet next Tuesday, ahead of a European Council meeting starting the next day.
The prime minister’s allies believe the cabinet will back her, although some ministers speculate whether two Eurosceptic ministers— international development secretary Penny Mordaunt and work and pensions secretary Esther McVey — might quit.
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