Nick Boles said there was “a lot of support” among mainstream Tory MPs for combining with opposition parties to prevent the UK crashing out of the EU without an agreement.
“I don’t care how many of my colleagues dream of this in the midnight hour. There are not the parliamentary numbers to support a no-deal Brexit,” he said.
“And I will vote, as a Conservative MP, in whatever way is necessary, on whatever motion will achieve the result of stopping a no-deal Brexit.”
Theresa May has insisted leaving without any agreement remains an option – despite her own civil servants warning of food and medicine shortages and huge tailbacks at the UK’s borders.
But The Independent revealed in June that pro-EU Tories are considering using a “humble address” – the tactic Labour used to force the government to release Brexit economic assessments – to block a no-deal exit.
Now Mr Boles, the former skills and housing minister, has echoed that readiness, arguing his party must pursue a “reasonable Brexit deal that everybody can live with”.
“I can think of 40 Conservative MPs – at least – who will not support a no-deal Brexit,” he told the Financial Times.
Such a revolt would almost certainly be sufficient to deliver a Commons majority to prevent the UK crashing out, teaming up with the opposition parties.
It would be likely to force the prime minister back to the negotiating table, perhaps with a request to the EU to extend the Article 50 deadline beyond March next year.
The crisis could also open the door to a fresh referendum, giving voters the option to remain in the EU, if the prime minister is unable to win parliament’s approval for her strategy.
A deal struck with some Tory rebels in June means a “meaningful vote” motion – to be tabled if no Brexit agreement has been struck by next January – cannot be amended.
Instead, MPs would merely be able to debate the stalemate, even with departure day from the EU little more than two months’ away at that point.
However, under parliamentary rules, a humble address can be laid by a group of backbenchers – as well as by the Opposition – and that vote is binding on the government.
Some pro-Brexit Tories simply believe the no-deal threat strengthens Britain’s hand in the exit talks – but others are desperate for that “clean break”, rather than to accept further compromise with Brussels.
In the interview, Mr Boles, a former supporter of remaining in the EU, condemned “intolerant, intemperate talk” obstructing a Brexit compromise.
“What we can’t allow is for one side to win and to grind the faces of the other side in the dust,” he said. “I put colleagues of mine in both camps squarely in my sights when I say that.”
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