The leader of Northern Ireland’s largest pro-British party has expressed optimism that the regional power-sharing government could be restored within days, urging ministers in London to move quickly to implement a deal between the sides.

Jeffrey Donaldson, leader of the Democratic Unionist Party (DUP), announced earlier on Tuesday that his party had endorsed proposals agreed with London on the operation of post-Brexit trade rules, and would end a near two-year boycott of the government.

The DUP had argued that London’s Brexit deal with the European Union undermined Northern Ireland’s place in the United Kingdom by demanding checks on some goods coming from Britain.

But London’s offer to cement Northern Ireland’s position in the UK in law, plus a 3.3 billion pound ($6.3 billion) financial package, looked set to win the DUP over.

The proposal would not require a renegotiation with the EU, a spokesperson for British Prime Minister Rishi Sunak said on Tuesday, adding that the agreement would not reduce Britain’s ability to diverge from EU regulations.

All sides want to move quickly before critics unpick the proposals and imperil the restoration of regional government, a key part of a 1998 agreement to end decades of sectarian violence.

Donaldson told BBC Radio Ulster the government could be restored within days “if the [UK] government moves with the speed that I believe they can”.

He said the legislation would have two elements; one designed to affirm Northern Ireland’s place within the UK, and the other amending the UK Internal Market Act to “protect the region’s ability to trade with the rest of the UK”.

“Have we achieved everything that we wanted to achieve?” he asked. “No, we haven’t. I will be honest with people about what we’ve been able to deliver.”

Chris Heaton-Harris, Britain’s Northern Ireland minister, said he looked forward to “the restoration of the institutions of Stormont [the Northern Ireland Assembly] as soon as possible”.

He declined to offer any detail on the deal, but said the two sides had achieved “quite a vast array of decent improvements to make sure our internal market works properly, as it should do”. If finalised in Northern Irish party talks on Tuesday, the proposals will be published on Wednesday.

London has kept its proposals under wraps to try to prevent them being undermined by hardened opponents of the post-Brexit trade deal with the EU.

Steve Baker, a junior Northern Ireland minister, tried to pre-empt concerns the changes might require Britain again to follow some EU regulations — which would infuriate advocates of Brexit.