DUP leader Arlene Foster has told RTÉ News that if British Prime Minister Theresa May wants the DUP's continued support, it means removing the Irish backstop from the Withdrawal Agreement.
In an exclusive interview with RTÉ News, Ms Foster said her party very firmly believes there is no need for the Irish Protocol, but if it is not removed she said her party will vote against the Withdrawal Agreement.
The DUP leader said if Mrs May could not get it through a meaningful vote then the Prime Minister had a decision to make.
Ms Foster said she did not believe Mrs May would have the numbers.
She must decide whether she goes back to European colleagues and say this is not acceptable to the British Parliament and therefore needs to be looked at again.
She said there was a sensible way through this, adding that all sides could commit to not putting a hard border on the island of Ireland.
Ms Foster said there was a political declaration dealing with the future relationship, and asked why a legally binding international treaty needed for the backstop.
She said it was not acceptable because it would become the "actuality" for people living in Northern Ireland.
The DUP leader reiterated that if she and Mrs May did not have "shared priorities" then the DUP would have to review the confidence and supply agreement.
She also referenced the apology which she made in her conference speech for the way her party had handled the Renewable Heat Incentive scheme.
She said it had been an incredibly difficult time, and said people needed to see that lessons had been learned and that those lessons were acted upon, to which she said she was committed.