Sinn Fein leader Mary Lou McDonald says a time-limited backstop in regards to a hard border in Ireland would be null-and-void.
The notion of a time-limited backstop was proposed for trade between the UK and EU after Brexit, with an “expected” end date of 2021.
It would see the UK match EU trade tariffs temporarily in order to avoid a hard border post-Brexit.
Ms McDonald echoed previous sentiments by Taoiseach Leo Varadkar that a time-limited backstop is not an option.
“The challenges presented to Ireland by Brexit are not temporary or fleeting, the protections afforded to this island must be robust and enduring.
“Anything that is time limited does not represent the back-stop that we need.
“Just bear in mind, that when the back-stop was first landed on, the Taoiseach assured people that Ireland had been protected, it was watertight, that it would ensure that people’s rights would be protected in an enduring way.
“Time limits are not acceptable, in fact I would render any arrangement null-and-void.”
Speaking before the party’s meeting on Thursday with the Taoiseach and the Tanaiste Simon Coveney, Ms McDonald said they would discuss Brexit and the current power-sharing impasse in Northern Ireland.
She said: “At the end of the last Dail session, we were told there would be renewed efforts at talks to reestablish the Assembly.
“It’s now October, there is no process, there is only stalling and excuses, people in the north are anxious to have their rights respected and legislated for.
“The DUP is in hiding at Westminster, their agreement with the Tories means that they are not willing, nor have been pressured to do the things necessary to ensure we have government again in the north.
“The DUP are obstructing the very thing that would protect the rights and entitlements of the people right across the north, they’re actually pursuing a strategy that will damage the interests of the people they represent.
“I find it to be a reckless position to adopt, but more reckless is that Theresa May has failed to challenge or face down the DUP.”
Mr Coveney said the vast majority of text of the withdrawal treaty had been agreed, but that the last 10-15% was proving difficult and that it mostly involved Ireland.
Discussing the DUP, Mr Coveney said: “The DUP are a very important voice in Northern Ireland but they do not represent a majority there.”
He said while the DUP had a special relationship with the British government, the Irish government had a relationship with all political parties in Northern Ireland.
Mr Coveney added he would be meeting EU chief negotiator Michel Barnier on Tuesday.