It would be “unacceptable” for the British government to sign up to an NI-only backstop as part of a Brexit deal, a DUP MP has said.
There are suggestions Boris Johnson could support such a proposal in order to break the current deadlock.
But Sir Jeffrey Donaldson said there would not be “unionist consent” for it.
The party’s chief whip was speaking before leader Arlene Foster meets the prime minister in London later on Tuesday.
The DUP’s meeting with Mr Johnson comes as pressure grows on Downing Street to reach a deal with the EU ahead of a key summit in October.
Boris Johnson has insisted he will not seek an extension to the Brexit deadline if there is no agreement with the EU.
In Dublin on Monday, Mr Johnson said he had an “abundance of proposals” to replace the Irish border backstop, the insurance policy to maintain an open border between Northern Ireland and the Republic of Ireland after Brexit, until a wider solution is found.
There is speculation he is considering returning to a backstop that would only apply to Northern Ireland – rather than the whole UK – an idea first suggested early in the Brexit negotiations.
Former PM Theresa May rejected an NI only bakstop in 2018 because she relied on the votes of the 10 DUP MPs in Parliament – but since taking office, Boris Johnson has lost his working majority and therefore, is no longer dependent on DUP votes.
The Irish government has said it is willing to look at a “Northern-Ireland specific solution”.
What was the NI-only backstop?
Proposed by the EU, it would have kept Northern Ireland in the EU’s customs union, which would have meant applying EU tariffs for goods entering NI from outside the EU customs union – including Great Britain.
It would also have applied EU single market rules for goods and animal products in Northern Ireland.
This would have got rid of the need for checks at the Irish border, but would have led to checks on goods passing between Northern Ireland and Great Britain.
It was criticised by the DUP and other unionist parties for “creating a border in the Irish Sea” and posing a risk to the union.
In February 2018, Theresa May said no prime minister could back such a proposal.
How does it differ from the backstop agreed by the UK and EU?
The main difference between the original backstop and the agreed solution is in relation to customs.
In the backstop agreed by the UK and EU in November 2018, the whole of the UK, would be included in a “temporary customs territory” with the EU.
Some pro-Brexit MPs claimed the backstop would be used to permanently trap the UK in the EU customs union, preventing the country from striking its own trade deals.
It would also see Northern Ireland staying aligned to some rules of the EU single market.
These arrangements would apply unless and until both the EU and UK agreed they were no longer necessary.
What has the DUP said?
The DUP insists it has been assured by Boris Johnson that he is not pursuing an NI-only backstop.
Sir Jeffrey told the BBC the proposal would “would run contrary to the principles at the heart of the Good Friday Agreement that say there should be no change to the relationship between Northern Ireland and Great Britain unless there is consent for it”.
“There would not be unionist consent for such an arrangement.”
On Monday night, DUP deputy leader Nigel Dodds said the party was prepared to look at “arrangements” to maintain all-island agri-food regulations – but only under a previously agreed role for the devolved assembly at Stormont.
“There may be some areas, where in certain areas of the economy where it’s to the benefit of Northern Ireland and the rest of the United Kingdom and the Irish Republic and the rest of the EU to have arrangements,” he said.
“These would have to be subject to the provisions of paragraph 50 of the Joint (report) which we inserted which is that the consent of the Northern Ireland Assembly – unionists and nationalists would have to apply so if all of that applies, then that is fine.”
What do other parties think?
Non-unionist political parties in Northern Ireland support the backstop and would be happy if the UK and EU agreed to an NI-only backstop.
The Ulster Unionist Party also opposes a backstop in any form, and claims unionists in Northern Ireland are being “hung out to dry”.
However, business and farming groups in Northern Ireland have urged support for a backstop, saying it is an acceptable way to protect cross-border trade.