Hopes of a Brexit deal at next month’s European Council received a blow on Sunday night when DUP leader Arlene Foster ruled out any concessions on customs and the regulation of goods.
Ms Foster said she could not accept any kind of internal customs border within the UK, adding Northern Ireland could not be part of two customs territories.
Her comments came as Taoiseach Leo Varadkar told The Irish Times that members of the Stormont assembly should play a part in the application of EU rules in the North after Brexit but time is running out to define what that role should be.
Speaking at the Conservative Party conference in Manchester, Ms Foster said her party would be open to discussing a time-limited backstop, the insurance policy to avoid a hard border in Ireland, but she noted Mr Varadkar had already rejected it.
Downing Street has also made clear that UK prime minister Boris Johnson is not interested in a time limit but wanted to scrap the backstop altogether.
Britain is expected to make formal proposals later this week for an alternative to the backstop in an attempt to agree a revised withdrawal agreement ahead of the EU summit on October 17th. The European Union and Irish Government have said any alternatives must achieve the same objectives as the backstop.