LONDON (Reuters) – Britain’s Brexit minister insisted a crucial vote on Prime Minister Theresa May’s Brexit deal would go ahead after a newspaper report on Sunday that she planned to delay it and make a last minute dash to Brussels to seek a better offer.

May’s deal looks set to be rejected by parliament on Tuesday, a decision that would throw plans for Britain’s exit from the European Union into turmoil and leave her own political future hanging in the balance.

The Sunday Times reported May was expected to announce on Monday that she was delaying the vote to head to Brussels to make a final appeal to the EU to improve Britain’s exit deal.

“The vote is on Tuesday, that is what we are focused on,” Brexit minister Stephen Barclay told BBC TV on Sunday.

“The risk for those who say simply go back and ask again, the risk is that isn’t necessarily a one way street, the French the Spanish and others will turn round, if we seek to reopen the negotiation, and ask for more,” he added.

Barclay said Britain would enter “uncharted waters” if it loses the vote, but May could stay on as prime minister.

European Union leaders are due to meet in Brussels on Thursday and there has been speculation that May might use that as a chance to press for changes to a deal that has angered both sides in the debate.

The strongest opposition to May’s deal centres around the so-called Irish “backstop”, an insurance policy designed to prevent a hard border between EU member Ireland and British-ruled Northern Ireland.

Brexit supporters and May’s nominal allies in Northern Ireland’s Democratic Unionist Party say it could leave Britain forced to accept EU regulations indefinitely, or Northern Ireland treated differently from the rest of the United Kingdom.

EU supporters say Britain would become little more than a rule-taker, offering the worst of all worlds.

Several lawmakers, including the DUP’s leader in the British parliament, Nigel Dodds, and former Brexit minister Dominic Raab, on Sunday called for May to go back to Brussels and seek to renegotiate the deal.

Former foreign secretary Boris Johnson, a leading Brexit campaigner who is seen as a possible successor to May, said lawmakers on all sides were united against the backstop and losing the vote in parliament would give May a mandate to ask the EU to remove it from the deal.

“Nothing is over until it is over,” he told BBC TV.

“If the prime minister is able to go back to Brussels this week and say I’m afraid that the Irish backstop solution that you have come up with is very unpopular … they will listen.”

While EU diplomats have said they could consider helping May with “cosmetic” changes to the non-binding political agreement that accompanies the deal, the legally binding text of the exit deal itself would be off limits to renegotiation.

The clock is ticking with Britain due to leave the EU on March 29, 2019.