The DUP has again rejected the Prime Minister's proposed Brexit deal as posing an "unacceptable" risk to the integrity of the UK.
Leader Arlene Foster confirmed the party would not support Theresa May if she tabled another meaningful vote in Parliament.
The party's 10 MPs have been propping up the Tory administration, and their view on Brexit has been key to the Government's prospects of securing agreement.
- WATCH: DUP Leader Arlene Foster confirms the party 'cannot' support the Prime Minister's Brexit deal if a fresh meaningful vote is called.
The DUP claimed Theresa May’s solution would trap Northern Ireland in the Irish border backstop insurance policy contained within the draft Withdrawal Agreement.
The party confirmed recent discussions with the Government had been good.
Asked about the pressure on the DUP to back the deal, Arlene Foster said it was not a case of "rescuing" Brexit.
"We very much want to see Brexit happening, we believe in Brexit, we believe in the opportunities that are there post-Brexit.
"We wish we were able to spend more time talking about the global opportunities that we believe are there for the nation post-Brexit.
"But instead we have become bogged down in a process, but that process has a Withdrawal Agreement with a backstop that will cause damage to the UK, and for us that is the critical point."
She pinned the blame on Mrs May, because the premier agreed to the backstop with the EU in December 2017.
The DUP leade added: "The most important issue for me, for the Democratic Unionist Party, for our 10 MPs, is the preservation of the union."