The DUP leader says the difficulties Theresa May faces over her Brexit plan are her ‘own making’.
Arlene Foster says the Prime Minister needs to stand up to EU leaders after failed attempts to get concessions to the withdrawal agreement in Brussels on Thursday.
The DUP, which is keeping the Government in power through a confidence and supply deal at Westminster, has vowed to vote against the draft treaty if the Irish border backstop is not binned.
The party believes the backstop plan would undermine the constitutional integrity of the UK by creating an economic border between Northern Ireland and Great Britain.
Mrs Foster says the Prime Minister needs to deliver on her promise to get legally binding changes if the deal is to get through Parliament.
Mrs Foster said: “The reaction by the EU is unsurprising. They are doing what they always do. The key question is whether the Prime Minister will stand up to them or whether she will roll over as has happened previously.
"This is a difficulty of the Prime Minister’s own making. A deal was signed off which the Prime Minister should have known would not gain the support of Parliament.
"If the Prime Minister had listened to our warnings and stood by her public commitments, we would not be in this situation.”