Brexit, the Northern Irish border and the backstop are likely to dominate Tory leadership hustings in Belfast.
Jeremy Hunt says there are technological solutions to the problem at the heart of the Withdrawal Agreement deadlock.
But people living on the border have dismissed that suggestion and Boris Johnson’s view that it can be resolved later.
Declan Fearon, who sells kitchens in Northern Ireland and the Republic, fears both contenders are making promises they cannot keep.
He said: “This is nonsense that we’re listening to, absolute nonsense to suggest that we’ll have all of this sorted in an implementation period that’s not going to allowed by the European Union.
“It is absolute nonsense and people here understand the nonsense that it is,” he added.
Boris Johnson told the DUP’s annual conference last year he would “junk the backstop” – the mechanism that keeps Northern Ireland in the customs union, if necessary, to avoid a hard border.
But in the third meaningful vote, the former Foreign Secretary backed the Withdrawal Agreement containing the backstop, much to the disappointment of the DUP friends in Belfast.
Owen Polley, co-author of ‘An Agenda for Northern Ireland after Brexit,’ said: “It’s fundamentally down to whether you trust Boris.
“The question is if it comes down to delivering Brexit or protecting Northern Ireland’s place in the Union, which will he choose?
“The DUP, they support Brexit but they believe that the Union is more important. Does Boris believe the same thing?”
Arlene Foster, whose party shores up the minority Tory government, says she has a good relationship with both potential leaders.
But the DUP will place more weight on keeping Northern Ireland in the UK than on exiting the European Union.