THERESA May is on a collision course with the Democratic Unionists today after making clear her commitment to some form of Irish backstop, which the Northern Irish party is determined to see scrapped.

The Prime Minister is due to meet Arlene Foster, the DUP leader, and her colleagues in Belfast this morning before she faces another Brexit showdown with EU chiefs Jean-Claude Juncker and Donald Tusk in Brussels on Thursday.

Mrs May in a speech to business leaders in Northern Ireland on Tuesday underlined how her commitment to avoiding a hard border with the Republic was “unshakeable”. She declared: "The UK Government will not let that happen. I will not let that happen."

But when asked how she could convince the people of Northern Ireland - a majority of whom voted to remain in the EU - to accept a Brexit deal, which was stripped of the backstop, the PM replied: "I'm not proposing to persuade people to accept a deal that doesn't contain that insurance policy for the future.

"What Parliament has said is that they believe there should be changes made to the backstop."

Mrs May stressed there was no suggestion her government was not going to ensure there would be a future provision to avoid a hard border.

“It's been called an insurance policy: the backstop. That ensures that if the future relationship is not in place by the end of the implementation period, there will be arrangements in place to ensure that we deliver no hard border."

Yet this puts her not only at odds with the DUP but also with many members of the Brexiteer faction in her own party.

Earlier on Tuesday, Ms Foster said: “Parliament's mandate is to replace the backstop. The current backstop…is toxic to those of us living in Northern Ireland and indeed for Unionists right across the United Kingdom because it would cause the break-up of the United Kingdom…"

Her use of the word “current” and her insistence she would not get caught up in the “semantics” of the backstop might give Downing St a glimmer of hope the DUP could be flexible.

However later, Sammy Wilson, the party’s Brexit spokesman, was adamant. “There is no alternative but to do what she has promised now to do and that is to go and have this agreement reopened and have the backstop removed.”

Asked if it was his party’s view was not simply to change the backstop but to have it scrapped altogether, he replied: “Yes. There are a number of reasons for that because the backstop is really designed to keep the UK as a whole in the customs union and the single market; that does not honour either her own manifesto or the outcome of the referendum.”

Reacting to the PM’s backstop comments in Belfast, a source from the European Research Group of Eurosceptic Tory MPs said: "Even if she doesn't mean what she said, we still do."

Today, the so-called Alternative Arrangements Working Group, chaired by Stephen Barclay, the Brexit Secretary, and attended by senior Leavers and Remainers in the Conservative Party, is due to meet again to try to flesh out details of the so-called Malthouse Compromise.

This involves replacing the backstop with a free trade agreement, involving technological solutions to avoid customs checks on the Irish border and extending by a year the post-Brexit transition period until December 2021.

Geoffrey Cox, the Attorney General, is also looking at legal means of introducing either a time-limit to the backstop or a unilateral exit clause both aimed at ensuring Britain’s time in a backstop would be temporary.

Asked if the PM would go to Brussels on Thursday with a fully-formed Plan B, her spokesman said: “I have never got into that and am not going to do that today."

At the weekly Cabinet, Mrs May urged senior colleagues to stop speculating about delaying Brexit, stressing how such talk was “counterproductive”.

Her exhortation came just 24 hours after a Cabinet minister told The Herald it was now “less likely” Britain would leave the EU on March 29 as planned because of the lack of parliamentary time to get the necessary legislation through Westminster by exit day.

This throws up the possibility the planned Valentine’s Day vote on a motion will involve an amendment to extend Article 50 to, say, the summer; a move the EU27 would have to agree to.

Meanwhile in Edinburgh, it emerged Nicola Sturgeon is to convene a special Brexit Cabinet meeting as her government steps up preparations for a no-deal outcome.

The First Minister will discuss contingency planning with her ministers next Wednesday, the day before MPs are due to hold another Brexit vote.

Later today, Michael Russell, the Scottish Government’s Brexit Minister, is due to tell Holyrood more about the SNP administration’s no-deal preparations.