The U.K. and the EU finally reached a deal after months of talks over contentious post-Brexit trade rules for Northern Ireland.

Already, both sides are pitching it as a major reset in frayed relations — but U.K. Prime Minister Rishi Sunak still has to sell it to skeptics in his own party and beyond.

The so-called “Windsor Framework” comes after a final day of talks between Sunak and European Commission President Ursula von der Leyen in Windsor.

In key developments Monday:

— Sunak and von der Leyen talked up the deal as a “new chapter” in EU-U.K. ties at a Windsor press conference.

— The U.K. PM urged his MPs to get behind him in a Commons statement, as key Brexiteers gave supportive early comments.

— Northern Ireland’s Democratic Unionist Party (DUP) vowed to study the text closely before deciding whether or not to back it.

— And Brexiteers in the U.K. hit out at No. 10 Downing Street over a meeting between King Charles III and von der Leyen on the same day a deal was struck.

‘New chapter’

Details of the new agreement are now being pored over by lawmakers on both sides of the English Channel, but the plan is aimed at easing customs red-tape, equalizing some tax rules across the United Kingdom, and giving Northern Ireland’s lawmakers more of a say over the future of the arrangement.

“The United Kingdom and European Union may have had our differences in the past, but we are allies, trading partners and friends, something that we’ve seen clearly in the past year as we joined with others to support Ukraine,” Sunak said at the joint press conference. “This is the beginning of a new chapter in our relationship.”

That line was echoed by von der Leyen, who said the plan would allow the two sides “to begin a new chapter,” and offer up “long-lasting solutions that both of us are confident will work for all people and businesses in Northern Ireland.”

Sunak — under pressure to hold a House of Commons vote on the agreement — told MPs Monday evening that the arrangement would end “burdensome customs bureaucracy” and “routine checks” on goods moving from Great Britain to Northern Ireland, and claimed he had “delivered what the people of Northern Ireland asked for … We have removed the border in the Irish Sea.”

He now faces the sizable task of convicing Brexiteer lawmakers on his own Conservative benches, many of whom will be closely watching the verdict of Northern Ireland’s fiercely anti-protocol DUP, to get on board.

“Our judgment and our principled position in opposing the protocol in Parliament and at Stormont has been vindicated,” said DUP leader Jeffrey Donaldson Monday night. “Undoubtedly it is now recognized that the protocol does not work. When others said there would be no renegotiation and no change, our determination has proved what can be achieved.”

Stormont brake

The protocol has been a long-running source of tension between the U.K. and the EU, and the two sides have been locked in months of talks to try to ease the way it works.

Under the arrangement, the EU requires checks on trade from Great Britain to Northern Ireland in order to preserve the integrity of its single market and avoid such checks taking place at the sensitive land border between Northern Ireland and the Republic of Ireland.

The DUP has been boycotting the region’s power-sharing government while it pushes for major changes to a set-up it sees as driving a wedge between Northern Ireland and the rest of the U.K.

Speaking at the press conference, Sunak and von der Leyen talked up a host of changes to the protocol that they hope will be enough to restore power-sharing in Northern Ireland.

Under the revised plan, goods moving from Great Britain but destined only for Northern Ireland will travel through a new “green lane” with fewer checks, while a separate, more stringent, “red lane” for goods at risk of moving on to the Republic of Ireland — and thereby entering the EU’s single market — will now operate.

Sunak said food retailers would “no longer need hundreds of certificates for every lorry” entering Northern Ireland, while food made to U.K. standards will be able to be freely sent to and sold in Northern Ireland. He also vowed that the new pact would scrap customs paperwork for people sending parcels to family or friends or shopping online.

UK PM Rishi Sunak and EU Commission president Ursula von der Leyen hope that the host of changes to the Brexit protocol announced today will be enough to restore power-sharing in Northern Ireland

The two sides have also amended the text of the protocol, Sunak said, to allow U.K. VAT and excise changes to apply in Northern Ireland — while a “landmark” settlement on medicines will mean drugs approved for use by the U.K. medicines regulator will be “automatically available in every pharmacy and hospital in Northern Ireland.”

And London and Brussels are now jointly pitching a new “Stormont brake,” claiming this will allow the devolved assembly in Northern Ireland — currently on ice amid a DUP boycott over the protocl — to prevent changes to EU goods rules “that would have significant and lasting effects on everyday lives” from applying in the region.

“This gives the institutions of the Good Friday Agreement in Northern Ireland a powerful new safeguard based on cross-community consent,” Sunak promised.

DUP’s next move

As he departed for London, DUP leader Jeffrey Donaldson said he and senior party colleagues would “take time to look at the deal” – a process likely to run at least through the weekend and to involve specially-commissioned analysis by constitutional lawyers. Early word from some Conservative Brexiteers was positive, with David Davis — who quit Theresa May’s government over her own EU deal-making — hailed it as a “a formidable negotiating success.”

Before flying out of Belfast, Donaldson briefed his party’s 25 members of the Northern Ireland Assembly about the expected key points. The DUP lawmakers met at Stormont, the seat of the power-sharing legislature that the DUP has blocked since May.

Donaldson said the DUP’s legal counsel would produce a detailed analysis for consideration by the party’s executive officers.

“It is vital that Northern Ireland’s place within the U.K. and its internal market is restored. We will have lawyers assess the legal text to ensure that this [is] in fact the case,” Donaldson told the Belfast News Letter, the main unionist newspaper in Northern Ireland.

Later, Donaldson told the BBC he was “neither positive nor negative” when assessing whether the DUP should accept the compromise package on offer.

“We need to take time to look at the deal, what’s available, and how does that match our seven tests,” he said, referring to the DUP’s July 2021 list of demands for “replacing” the protocol.

Other DUP officials said the party’s senior leadership would convene at party headquarters in Belfast, possibly on Saturday, to review the party’s legal verdict on the deal – and whether concessions won by the U.K. government were sufficient to end the DUP’s obstruction of power-sharing at Stormont.

Donaldson will seek maximum support at that meeting before committing to any policy pivot on the protocol. Other senior officials, including former deputy leader Lord Dodds, have explicitly rejected the idea of reviving Stormont if the revised protocol agreement retains any oversight role for the CJEU. Both Donaldson and the DUP’s “seven tests” have stopped short of drawing this red line.

Ever since narrowly losing May’s assembly elections to the Irish republicans of Sinn Féin, the DUP has refused not only to form a new cross-community government – the assembly’s central function under terms of Northern Ireland’s 1998 peace accord – but also has blocked the election of a neutral speaker for the assembly, preventing it from sitting.