Boris Johnson is facing “certain” defeat in a vote that would prevent him imposing fresh Covid-19 restrictions behind the backs of MPs, after opposition parties joined a Tory revolt.

The prime minister is expected to be forced into another U-turn, as cross-party pressure grows to rip up draconian emergency laws that, one Conservative rebel said, mean “liberty dies”.

Up to 60 Tory MPs are now backing the move, with the scales tipping against the government when Labour and the Liberal Democrats said they were poised to do the same.

Former Commons Speaker John Bercow weighed in, saying that continuing to bypass MPs in the handling of the pandemic was part of a “toolkit of Trumpianism”.

Demanding “accountability to parliament”, Mr Bercow said: “Ducking, diving, dodging scrutiny, of which there has been some evidence in recent times, cannot continue.”

Tory rebel Steve Baker, when asked if they had the numbers to defeat the government – with opposition support – replied: “I’m certain at the moment.”

About 50 law changes are believed to have been made under the emergency laws, which were rushed through at the start of the pandemic in March and are up for renewal on Wednesday.

“MPs should be sharing in the dreadful burden of decision in these circumstances and not just retrospectively being asked to approve what the government has done,” Mr Baker told Sky News.

“How do people think that liberty dies? It dies like this, with government exercising draconian powers, without parliamentary scrutiny in advance, undermining the rule of law by having a shifting blanket of rules that no one can understand.”

Oliver Dowden, the culture secretary, attempted to hold the line, saying it was vital that ministers had the power to “move quickly” in bringing necessary coronavirus rules.

He confirmed that a vote on the introduction of the “rule of six” would be rushed forward to this week to try to calm the revolt – but that falls far short of the rebels’ demands.

The crucial amendment has been put forward by Graham Brady, the chairman of the Tory 1922 committee, and enjoys prominent backers.

They include former party leader Iain Duncan Smith; Damian Green, who was effectively Theresa May’s deputy; former Brexit secretary David Davis; and Harriet Harman, Labour’s former deputy leader.

If all the opposition parties support the rebel amendment – the SNP is also expected to – only 43 Tories would be needed to defeat the government.

Jo Stevens, Labour’s culture spokesperson, said the party had “sympathy” with the amendment, adding: “I think that the likelihood is that we would back it.”

Labour, which has supported all crackdowns introduced so far, could then pursue votes to exploit divisions on the Tory benches, where opposition to restrictions is growing.

Mr Baker said they did not “really want a rebellion”, preferring to work with the government to reach agreement without embarrassing ministers.

“Let’s have policies that enjoy our consent,” he said, adding: “I back Boris Johnson. I want him to succeed.”

A new poll on Saturday showed that Labour has overtaken the Tories for the first time since Sir Keir Starmer became leader in April, with a three-point lead.

Mr Dowden said: “I think it’s important in a crisis like this, when things are moving very rapidly, that the government has the power to move quickly – and that is the power that the government was given through the initial legislation earlier this year.

“But then it is important that MPs hold us to account and vote on that, and that is exactly what is happening here.”