LONDON (AP) — British Prime Minister Theresa May's parliamentary allies are warning they could remove support from her minority government if she does not alter her Brexit deal with the European Union.

Northern Ireland's Democratic Unionist Party struck a deal last year to back May's Conservatives on major legislation. But the Protestant, pro-U.K. party opposes the Brexit deal's plans for keeping the border between Northern Ireland and Ireland open after Brexit.

In a warning to May, DUP lawmakers abstained late Monday during several votes on finance bill, and voted against the government on one amendment.

DUP lawmaker Sammy Wilson said the votes were "designed to send a political message to the government."

Writing in Tuesday's Belfast Telegraph, May said the deal "puts Northern Ireland in a fantastic position for the future."