No fewer than 74 per cent of Conservative MPs say they want an end to freedom of movement in March 2019, while 63 per cent oppose a continued remit for the European Court of Justice.
Yet the EU has made clear that both those conditions will be imposed in any transition deal, for around two years or longer – and the Prime Minister has signalled that she will accept them.
Furthermore, the study found that 65 per cent of Tory MPs favour crashing out of the EU rather than accepting a bad deal, more than the 60-80 previously thought.
The findings appear to increase the danger that Conservatives will refuse to accept the deal that Mrs May is expected to strike later this year, in time for a Commons vote in the autumn.
They also make it more likely that the Prime Minister will face a leadership challenge if she defies her party and attempts to force through a “standstill” transitional agreement.
Professor Tim Bale, from Queen Mary University of London, who helped conduct the survey, said: “The sheer number of Tory MPs seemingly prepared to countenance crashing out of the EU without a deal is one of the most striking findings to emerge from this research.
“Who knows, though, if push does come to shove, whether they really will refuse a compromise? If they do, then Theresa May could be in some serious parliamentary trouble later on this year.”
And Professor Anand Menon, director of the UK in a Changing Europe think-tank, said: “Brexit presents a stark challenge to the leaderships of both major political parties. Their views are at odds with those of their own MPs.
“The Prime Minister, in particular, might face considerable opposition from her own backbenchers when it comes to securing the kind of transitional deal she has indicated she wants.”
Ipsos MORI interviewed 105 MPs in private, face to face, with the findings weighted to reflect the composition of the House of Commons.
The survey, for UK in a Changing Europe, also exposed the chasm between the expectations of Conservative and Labour MPs for a successful Brexit.
The Tories were upbeat for the economy, with 89 per cent believing it will get better over the next decade and 80 per cent in of favour leaving the single market and negotiating a bespoke trading deal with the EU.
In stark contrast, 44 per cent of Labour MPs believe the economy will get worse and 83 per cent fear that any future trade deals will leave Britain worse off.
For that reason, the poll also set out the growing pressure on Jeremy Corbyn to change course by pushing for the UK to stay in the single market and customs union permanently.
It found that 90 per cent of Labour MPs think staying in the single market is compatible with Brexit – something the Labour leader has insisted is impossible.
Source: The Independent