Theresa May faces being publicly denounced by her Cabinet’s most senior Brexiteers if she steamrolls their objections to her favoured plans for a customs deal with the EU, senior figures have said.

Cabinet sources warned the Prime Minister not to attempt to force through a “hybrid” proposal which they said would fail to meet promises made during the referendum campaign and in the Tories’ 2017 manifesto.

Senior figures also warned that Britain was “losing time” in the negotiations both because of the delay in Mrs May making a final decision on a plan for future customs arrangements, and as a result of No 10 putting off a Commons vote on keeping the UK in the tariff-free customs union.

Downing Street this week said work on the two options for a customs deal was “ongoing”, after Brexiteers, backed by Sajid Javid, the new Home Secretary, and Gavin Williamson, the Defence Secretary, opposed No 10’s plans for a customs partnership in which Britain would collect tariffs on behalf of the EU and companies would have to claim back rebates.

Both sides admit neither proposal is “perfect”, but Brexiteers say the hybrid partnership arrangement would prevent free trade deals being struck and is a “Trojan horse for a customs union”.