The DUP Westminster leader Nigel Dodds said he would rather the UK remain in the European Union than back Theresa May’s withdrawal agreement and urged the government to return to Brussels to get changes to the border backstop.
The DUP are concerned that the backstop would create a border down the Irish Sea by placing checks on goods coming into Northern Ireland from Great Britain.
Mr Dodds said on BBC Newsnight: “I would stay in the European Union and remain rather than risk Northern Ireland’s position. That’s how strongly I feel about the union.”
Mr Dodds said the DUP, which prop up the Conservatives in government, had made clear they would not support Mrs May’s withdrawal agreement unless the backstop protocol was changed.
All ten of the DUP MPs dealt a blow to Theresa May on Friday when they voted against her deal for the third time.
Talks are continuing between ministers and the party in a bid to get its support for a possible fourth vote on the withdrawal agreement.
The Irish taoiseach Leo Varadkar has been adamant that the EU will not budge on the issue.
On Friday night he tweeted: “The European Council has agreed unanimously that the withdrawal agreement will not be reopened.”
DUP leader Arlene Foster has said: “We have encouraged the government to return to Brussels on these issues and not simply to accept the position of the European Union as being unalterable.”
Mrs May saw her third Brexit deal defeated in the House of Commons by 344 votes to 286, which meant the UK missed a deadline to delay Brexit to May 22.