Nick Boles says if Theresa May fails to secure an extension to keep UK in trade bloc until 2022 he’ll force a vote

A new Commons rebellion to keep Britain in the EU’s customs union for years after Brexit is being prepared by a former Tory minister.

Nick Boles, a former business minister, said he wanted Britain to remain in the customs union until early 2022, allowing more time to come up with a viable long-term plan.

He said that, if the government did not formally adopt the idea of extending Britain’s membership, he was prepared to force a vote on the issue by attempting to add his plan to the EU withdrawal bill, currently working its way through parliament.

His comments come soon after Theresa May made a major breakthrough by convincing her cabinet to back a plan under which Britain could stay inside elements of the EU’s customs union and single market.

The “backstop” option is designed to ensure there is a frictionless Irish border and would kick in should other solutions fail to materialise. However, cabinet Brexiters are demanding that it is strictly time-limited.

In a blow for May, however, sources in Brussels suggested that the EU had serious reservations about allowing the government to apply the backstop option to all of the UK without outlining a long-term solution. Sources said that it was only ever designed as a special deal for Northern Ireland. Britain would not be able to leave the EU “bit by bit”.

Remaining inside the customs union would mean the UK would not be able to sign its own trade deals – one of the key Brexit gains cited by Leave supporters. However, Boles said he believed his compromise plan for a temporary extension to Britain’s membership would win significant support from Leave and Remain MPs.

“I am encouraged by reports that the PM is exploring an extension to the UK’s participation in a customs union after the end of the transition in December 2020,” he told the Observer. “I hope this will become the government’s preferred policy.

“But if it does not, I am ready to lay amendments to the withdrawal bill and am confident of securing significant support from pragmatic colleagues who, like me, want to see a Brexit that works.”

Business leaders are increasingly vocal in their calls for Britain to remain inside the customs union, which would solve many of the issues threatening to cause serious delays at the border after Brexit. Paul Drechsler will use his last major speech as the CBI’s president this week to call for an end to Brexit dithering, which has been “a handbrake on our economy”.

“We need to break the Brexit logjam and fast, because there’s so much more that we need to get on with,” he will say. “A pragmatic decision to be in a customs union with the EU would allow us to move on. We can then … tackle the root causes of low productivity and unacceptable regional inequality in our country.”

May names nine new Tory peers to bolster party after Brexit defeats Read more

An Opinium poll for the Observer also suggests a shift towards support for staying in the single market. In January 2017, 41% wanted to end free movement – and were prepared to leave the single market to do so. Only 32% wanted to stay in the single market, even if it meant keeping free movement rules. This month, however, 40% wanted to prioritise staying in the single market, while only 34% wanted to prioritise ending free movement. The poll also gives the Tories their biggest lead since the general election. They are up three points on 43%, four ahead of Labour.