Steve Baker, who quit over the Chequers blueprint in July, said there would be a 'massive problem' unless it was ditched before party conference at the end of this month

Theresa May will trigger a 'catastrophic split' in the Tories if she tries to force through her Chequers plan, a former Brexit minister warned today.

Steve Baker, who quit over the blueprint in July, said there would be a 'massive problem' unless it was ditched before party conference at the end of this month.

He said as many as 80 Conservative MPs could vote against the proposals if they are put to the Commons.

Some 25 have now publicly signed up a 'Standup4Brexit' campaign vowing to oppose Chequers.

They include former Cabinet ministers Iain Duncan Smith, Priti Patel and Owen Paterson.

The warning comes as the PM faces a huge backlash against her policy - which would see the UK follow EU rules and collect some taxes on behalf of the bloc in order to keep trade flowing freely.

Boris Johnson delivered an extraordinary attack on Mrs May's position yesterday by likening her approach to wrapping a 'suicide vest' around the British constitution.

But the premier is caught in a pincer movement as Tory Brexiteers and Remainers who are both threatening outright revolt unless they get concessions.

Justice Secretary David Gauke tried to rally support for Mrs May this morning, saying there was 'no alternative plan'.

'There isn't an alternative credible plan out there,' he told BBC Radio 4's Today programme.

'I think that it is absolutely right that the Cabinet and the parliamentary party backs the Prime Minister.

'In challenging circumstances she is the right person to deliver the right deal for this country.'

Theresa May (pictured at No 10 today) will trigger a 'catastrophic split' in the Tories if she tries to force through her Chequers plan, a former Brexit minister warned today.

The PM was boosted today by claims that the EU is preparing to take a more conciliatory approach in negotiations.

What is in Theresa May's Brexit blueprint? These are some of the key features of the Chequers plan being pushed by the UK government: A new free trade area in goods, based on a 'common rulebook' of EU regulations necessary. This will require the UK to commit by treaty to match EU rules

'Mobility' rules which will end automatic freedom of movement, but still allow UK and EU citizens to travel without visas for tourism and temporary work. It will also enable businesses to move staff between countries.

Continued UK participation in and funding of European agencies covering areas like chemicals, aviation safety and medicines

A 'facilitated customs arrangement', removing the need for customs checks at UK-EU ports. It would allow differing UK and EU tariffs on goods from elsewhere in the world to be paid at the border, removing the need for rebates in the vast majority of cases. This is designed to avoid the need for a hard Irish border. But in theory it still allows Britain to sign trade deals.

Keeping services - such as banking or legal support - outside of the common rule book, meaning the UK is completely free to set its own regulations. It accepts it will mean less trade in services between the UK and EU.

Continued co-operation on energy and transport, a 'common rulebook' on state aid and commitments to maintain high standards of environmental and workplace protections.

A security deal allowing continued UK participation in Europol and Eurojust, 'co-ordination' of UK and EU policies on foreign affairs, defence and development.

Continued use of the EHIC health insurance card. Advertisement

The EU’s 27 remaining leaders are expected to discuss whether to issue additional guidance to Michel Barnier, the bloc’s chief negotiator, at an informal summit in Salzburg, Austria, later this month.

If approved, the update to Mr Barnier’s instructions would ‘serve as a sort of mandate to do the deal’, according to a senior EU diplomat quoted by the Financial Times.

However, Mr Baker insisted Mrs May abandon her Chequers compromise and pursue a more conventional free trade deal.

'We are reaching the point now where it is extremely difficult to see how we can rescue the Conservative Party from a catastrophic split if the Chequers proposals are carried forward,' he said.

'I am gravely concerned for the future of our party… because I recognise that the Labour opposition represents a severe danger to our security and prosperity.'

Mrs May has ordered her chief of staff Gavin Barwell and communications director Robbie Gibb to sell the Chequers plan to backbench MPs at a series of dinners this week.

She will also convene a special meeting of the Cabinet on Thursday to co-ordinate contingency plans for the possibility of a no-deal Brexit.

Meanwhile, former Cabinet ministers David Davis and Owen Paterson will outline proposals designed to overcome the Irish border issue that has dogged the Brexit talks.

Eurosceptics will push ahead tomorrow with a major new study on the impact of a no-deal Brexit. The report by the Economists for Free Trade group dismisses 'hysteria' over predicted food shortages and says the UK economy would benefit from trading on World Trade Organisation terms.

Jacob Rees-Mogg, chairman of the European Research Group of Tory MPs, said: 'We have nothing to fear from trading on WTO terms… Let Brexit mean Brexit and let us flourish under the auspices of the WTO.'

The document says UK exports to WTO countries have risen three times faster than those to the EU over the past 25 years.

Theresa May (pictured on the way to church with the Queen near Balmoral yesterday) is struggling to hold the Tories together amid divisions over Brexit