British Prime Minister Theresa May speaks to the media at the end of European Council in Brussels, Belgium, on Nov. 25 after the leaders of the 27 remaining EU member countries endorsed the draft Brexit withdrawal agreement. On Sunday, May said the Parliament will enter "uncharted waters" if they don't approve the deal. Photo by Julien Warnand/EPA

Dec. 9 (UPI) -- Britain's Prime Minister Theresa May has a warning to members of Parliament: You'll be in "uncharted waters" if you don't back my Brexit deal.

She is facing a revolt from some members of her own Conservative Party ahead of Tuesday's schedule vote in the House of Commons on leaving the European Union. Opposition includes her arrangement for the Northern Ireland border.


"If you want Brexit, make sure you get it, and that's about this deal," she said to the Daily Mail. "When I say if this deal does not pass we would truly be in uncharted waters, I hope people understand that this is what I genuinely believe and fear could happen. It would mean grave uncertainty for the nation with a very real risk of no Brexit or leaving the Europea."

She also rejected a second referendum vote -- 1 1/2 years after citizens approved Brexit -- despite calls by lawmakers.

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"We had a people's vote, that's what frustrates me when people talk about this, the second referendum being a people's vote, " May said. "We had a people's vote, let's deliver on the first people's vote."

Around 100 members of her coalition are opposing her Brexit deal: Labor, Liberal Democrats, Scottish National Party and Northern Ireland's Democratic Nationalist Party. The House of Commons has 650 members.

Conservative lawmaker Esther McVey, who quit the Cabinet over the Brexit deal last month, warned if the proposal is defeated, May should "immediately" return to the European Union to "get a better deal" if she loses in the Commons in an interview on Sky News on Sunday.

"At the moment I am looking for a person who can unite the party behind a Brexit deal, a person who believes in Brexit, who's got, really, the full passion to deliver that," said when asked whether she would seek to replace May.

Boris Johnson, the former foreign secretary, said Britain will be open to "blackmail" if the deal is approved.

"The real problem with the backstop arrangement is it gives the power to Brussels and to all the other EU member states effectively to blackmail us and to get what they want out of the future trade negotiation," Johnson told the BBC. "It is a diabolical negotiating position."

Brexit Secretary Steve Barclay said Sunday the vote will go ahead Tuesday, but May will make a final decisio nMonday on whether to delay it.

If May loses a no-confidence vote Tuesday, Christmas Day would be the last chance for any coalition to try to win a Commons majority.