I N WESTMINSTER THE Democratic Unionist Party is hot for Brexit and implacably opposed to Theresa May’s deal, contributing to the stormy atmosphere. At home, however, Northern Ireland’s largest party faces trouble of its own. Brexit has opened up a new division in a place that has no shortage of them. This one pits the DUP against many of its erstwhile supporters in business and farming.

Since last year’s general election, Mrs May’s government has been propped up by a “confidence and supply” agreement with the DUP , under which the party backs her in crucial votes. Now, however, the party accuses her of betraying Unionist interests in Northern Ireland. It is particularly outraged by the part of the EU withdrawal agreement known as the backstop, which could lead to the province retaining different regulatory arrangements from the rest of the UK —and thus, in Unionist eyes, becoming less British. The DUP argues that Mrs May’s deal is worse than no deal, and warns that she can no longer rely on them for support in the House of Commons.

Fretful businesspeople in Northern Ireland are urging the DUP to change course. The strength of feeling was illustrated by Bill Wolsey, a prominent Belfast hotelier, who received thunderous applause at a business event when he declared: “We’re represented by politicians, some of whom have the vision of Blind Bart and some who are weighted down heavily by prejudice from the past.” Calling on the party to support Mrs May’s approach, he added: “We in the business community, and the voters of the future, should never forgive them if they don’t take this opportunity.”

It is easy to see why businesses worry about crashing out of the EU without a deal. Fully 27% of Northern Ireland’s exports go south to Ireland and 23% of the province’s imports come from there. The restoration of any sort of border, with consequent customs checks and delays, would hit farmers particularly badly. A third of those exports to the Irish Republic are of food and live animals. The powerful Ulster Farmers’ Union has given its backing to Mrs May’s deal, even though many of its members are likely to be DUP supporters.

In the 2016 referendum, 56% of voters in Northern Ireland plumped for Remain, 44% for Leave. The general belief is that a large majority of Nationalists were for Remain, while Unionist voters were split. There are no signs of Nationalist recruits to the Brexit cause since the referendum, while on the Unionist side there is an almost eerie silence. There have been none of the big rallies or demonstrations so often held by the DUP .

Many ordinary Unionists remain keen on Brexit. Echoing arguments often heard in mainland Britain, one community leader in a County Antrim town explains: “Round here the one big issue is immigration. Working-class Protestants and Unionists just don’t like immigration.” The DUP seems unlikely to back down. It has dismissed the likes of Mr Wolsey as puppets “dancing to the government’s tune”.