A minority party propping up Theresa May's government has threatened to trigger the collapse of her government if London strikes a deal on Brexit that separates the Northern Ireland economy from the rest of the UK.
Sources in the Belfast-based Democratic Unionist Party told broadcasters that it was determined to block any deal that left the region uniquely tied to the EU economy. "It is unacceptable that we would be treated differently to the rest of the UK," a report quoted the party official as saying. "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."
The party said it could even trigger a general election by voting down the budget due at the end of the month. Mrs May has 315 lawmakers and governs with a working majority of 13 thanks to a deal with the 10 lawmakers of the DUP though rebels in her own party say 40 of her MPs could vote against her deal.
Balanced against this a group of between 30 to 40 Labour lawmakers could defy their leader, Jeremy Corbyn, and vote for a deal.
The EU's Brexit negotiators believe a divorce deal with Britain is "very close", diplomatic sources told Reuters last week, though it is unclear whether May could get the deal approved by the British parliament.
Around 320 votes in the 650-seat parliament are needed to be certain of winning a vote.
In one scenario being discussed, Labour lawmakers would initially vote down any deal to prove loyalty to the leadership, but if parliamentary deadlock remained the rebels would back any deal that prevented a chaotic departure.
If lawmakers reject a deal, May could fall and Britain would face leaving the EU without an agreement, a move investors and company chiefs say would weaken the West, panic financial markets and block the arteries of trade.
Without a deal the United Kingdom would move from seamless trade with the EU to customs arrangements set by the World Trade Organisation for external states.