Will Northern Ireland’s largest pro-UK party accept new Brexit trade rules?

London and Brussels are closing in on a deal to reform contentious post-Brexit trading arrangements for Northern Ireland, but there is no guarantee that the region’s largest pro-UK party will accept it.

The Democratic Unionist party is warning that an agreement between the UK and the EU that falls short of the DUP’s demands would mean protracted political gridlock in Northern Ireland, with no fully functioning devolved government.

The DUP backed Brexit but opposes the so-called Northern Ireland protocol, part of Britain’s withdrawal agreement with the EU, which sets out the region’s trading arrangements. The protocol places a customs border inside the UK and leaves Northern Ireland within the EU single market for goods, bound by the bloc’s rules.

Hardliners in the DUP say that London can have the protocol, or the Good Friday Agreement, which ended three decades of conflict in 1998 and is effectively Northern Ireland’s political constitution — but not both.

Unionists argue that the protocol undermines the principle of cross-community consent that was enshrined in the 1998 peace deal.

“The last thing the [UK] government should do is just . . . roll over [the concerns of] unionists. That would be just crazy, it wouldn’t work,” former Irish taoiseach Bertie Ahern, who signed the landmark deal in 1998, told a seminar in Belfast on Tuesday.

Ahern’s comments came as negotiators briefed Rishi Sunak, UK prime minister, that a deal is taking shape with the EU to resolve the dispute over the Northern Ireland protocol. The UK wants reduced checks on goods heading from Great Britain to Northern Ireland, among other things.

An agreement has not been finalised and serious problems remain, according to officials in London and Brussels — although both sides hope a deal can be clinched before the 25th anniversary of the Good Friday Agreement on April 10.

Sunak will face a test of his authority if whatever is agreed triggers a rebellion by hardline Brexiters in his Conservative party and proves unsellable to the DUP.

The party, which claimed betrayal when the then prime minister Boris Johnson backtracked on his promise to never put a customs border for goods in the Irish Sea, is already bracing to be left in the lurch again.

The DUP is against the customs border in the Irish Sea — which it says compromises Northern Ireland’s place in the UK — and wants an end to oversight of the trading arrangements by the EU’s top court.

DUP leader Sir Jeffrey Donaldson — who like Sunak is under pressure from hardliners in his party — pulled his first minister out of Northern Ireland’s power-sharing executive at Stormont a year ago, and has boycotted devolved government since elections last May that were won by pro-Irish unity party Sinn Féin.

Despite the party’s tough tactics, Edwin Poots, who was briefly DUP leader in 2021, said it was “entirely possible” that an agreement about the Northern Ireland protocol would fall short of its demands.

He told the Financial Times: “We can’t go back into government until this is satisfactorily resolved. This isn’t about being stubborn or difficult . . . Stormont will be locked down for two years if that’s what it takes . . . I’m not a devolutionist at any price.”

Donaldson welcomed that London and Dublin now concede that it was a “mistake” to proceed with the protocol, agreed in 2019, without support from the unionists, but insisted they needed to go further.

“Whilst this recognition is good, I would like to see their commitment to ensuring the mistakes of 2019 are not repeated in 2023,” he said.

DUP MP Jim Shannon told a parliamentary committee at Westminster on January 23 that any protocol agreement over the head of the party “would raise much passion and fire among the unionist community”.

A recent Lucid Talk opinion poll found that two-thirds of unionist voters supported the DUP staying out of Stormont until there are significant changes to the protocol, or it is scrapped completely.

Support for the DUP’s harder line rival, the Traditional Unionist Voice, has risen two percentage points to 7 per cent since November, while the DUP’s support dropped two points to 25 per cent.

Nevertheless, it will be a tall order for any protocol deal to satisfy the “seven tests” the DUP has said are its yardstick for returning to Stormont.

“Once there is a deal, Donaldson has a cataclysmic decision to make because we know it isn’t going to meet the tests,” said one former DUP special adviser.

Under the Good Friday Agreement — a deal that the DUP opposed at the time — nationalists and unionists each have a veto over the power sharing executive.

“If the assembly goes, it could be gone for a very long time,” said Sarah Creighton, a unionist commentator. “The longer that building stays shut, the more people in Northern Ireland lose faith” in devolved rule.

The former DUP adviser predicted the party would initially reject whatever deal is reached on the Northern Ireland protocol, try to wring more concessions, but eventually swallow it. “Whichever way you slice it, it would be a humiliating climbdown,” he said.

But imagining Brussels will get rid of oversight of Northern Ireland’s trading arrangements by the European Court of Justice is “a bit of an indulgence”, said another former DUP official. “I don’t think we are going to get satisfaction on the easy issues, let alone the hard issues,” he added.

Donaldson has played tough before — he walked out of the Ulster Unionist party’s Good Friday Agreement delegation on the day it was signed and later defected to the DUP.

But the DUP has also U-turned: it did not initially oppose the protocol but changed tack after a poll in February 2021 showed a plunge in support for the party.

“They are masters of self-preservation,” said one former UUP official. “Never underestimate what the DUP might do.”