The government should have made clear after the 2017 election that it would “inevitably” have to accept a closer relationship with the EU after Brexit, the Tory chief whip has said.
In a BBC documentary, Julian Smith – who manages party discipline – is also critical of the cabinet’s behaviour.
The attack comes as the cabinet is split over whether to move to a softer deal that could mean a customs union.
MPs will hold further votes later on Brexit options to resolve the deadlock.
A customs union with the EU is thought to be the most popular of the ideas under consideration.
Other options include leaving the EU without a deal on 12 April, a referendum to rule out no deal and a confirmatory referendum on Prime Minister Theresa May’s deal.
In interviews for The Brexit Storm: Laura Kuenssberg’s Inside Story, Mr Smith accused ministers of trying to undermine the prime minister.
He said he witnessed ministers “sitting around the cabinet table… trying to destabilise her [Mrs May]” and described their behaviour as the “worst example of ill-discipline in cabinet in British political history”.
Mr Smith said that when his party failed to get a majority in the 2017 election, which ended in a Hung Parliament, “the government as a whole probably should have just been clearer on the consequences of that”.
The parliamentary arithmetic after the poll, he added, meant “that this would be inevitably a kind of softer type of Brexit”.
But Chief Secretary to the Treasury Liz Truss told BBC Radio 4’s Today programme: “It’s not clear to me that going softer is the way to command support.
If you look at the parliamentary arithmetic now, it’s not clear that something like a customs union actually commands support.”
She said MPs, so far, had not been in favour of a customs union and the “answer lies in modifications to the prime minister’s deal”.
