The two contenders to be Britain's next prime minister both say they will scrap a contentious Irish border provision that has hamstrung efforts to approve a divorce agreement with the European Union.
Jeremy Hunt and Boris Johnson are competing to replace Prime Minister Theresa May, who is quitting after Parliament rejected her Brexit deal.
A key sticking point is a measure known as the backstop, designed to maintain an invisible border between Northern Ireland and EU member Ireland.
EU leaders say there can be no withdrawal agreement without it, but Brexit-backing UK lawmakers reject it for keeping Britain bound to the EU.
Hunt said Tuesday "we are never going to have a deal to leave the EU with the backstop", while Johnson said May's withdrawal agreement "is a dead letter."
Johnson said the Irish border issue could be resolved during trade talks.
"The backstop really represents I am afraid the incoherence at the heart of the strategy that we have been pursuing for the last few years - we have been wanting to come out of the EU supposedly while actually being prepared to stay in the customs union and in full regulatory alignment," Johnson said in a election hustings in Northern Ireland.
"That is tantamount to coming out of the EU, but being run by the EU.
"So what I think people in this country want is to come out as the whole of the UK, and solve the issues of the backstop in the context of the FTA and use the opportunities that Brexit brings us to do things differently."
