Rees-Mogg heaps pressure on prime minister

If the backbencher were to gain the support of all the members of the ERG they could force a leadership challenge.

He claimed the government had proposed ‘over-complicated’ solutions to the customs problem and must be prepared to tell Brussels it will walk away without paying the £40 billion Brexit divorce bill – potentially leaving the bloc in the red.

Appearing on the Andrew Marr Show Rees-Mogg said May had made a mistake over her approach to the Irish border issue by ruling out the prospect of unilaterally keeping an open frontier after Brexit.

He said: ‘The prime minister said in her Mansion House speech that she wasn’t going to do this, I think that is a mistake.

‘I think it is the obvious negotiating position to have. Bear in mind the Irish economy is heavily dependent on its trade with the United Kingdom, it is overwhelmingly in the interests of the Republic of Ireland to maintain an open border with the United Kingdom.

‘I think, if you are going into a negotiation, you should use your strongest cards and just to tear one of them up and set hares running on other issues is, I think, an error.’

He added that the government’s plans for a ‘backstop’ which would see the whole UK potentially tied to European Union rules in order to avoid a hard border – if no other way of solving the issue is possible – was ‘a real problem’ and could leave the UK a ‘vassal state for an indeterminate period’.

‘Basically, the deal is very simple – we are paying a very large amount of money, £40 billion, and in return we want a trade deal.

‘Everything else is essentially incidental to that,’ he said.

He added that the UK should make clear to the EU that ‘if we don’t get the trade deal we want, you don’t get the money’. Without the UK’s money the EU ‘faces a real crisis next March’ – when the political situation in Italy meant it was already facing other problems.

But even after firing his Brexit salvo Rees-Mogg insisted he believed May was ‘the most impressive and dutiful leader this country has had’ and was ‘crucial to the Brexit project’.

‘Of course I wouldn’t challenge Theresa May, that’s a ridiculous idea,’ he said.

Appearing on Sky’s Sophy Ridge on Sunday former Conservative leader Iain Duncan Smith said anyone plotting to overthrow May should ‘shut up’ and get on with delivering Brexit.

Meanwhile on Peston on Sunday Labour’s deputy leader Tom Watson said no decision had yet been made on whether the party’s MPs would be whipped to oppose membership of the single market when the Commons votes on the issue in June.

‘We haven’t decided our whipping arrangements yet,’ he said. ‘We haven’t made a decision yet, but we’ve been pretty clear that there are deficiencies in the Norway model that might not work for a bespoke UK deal.’