More than 40 cross-party MPs, including Labour’s Harriet Harman and Conservative Iain Duncan Smith, are backing an amendment to force a vote in parliament on future Covid-19 restrictions amid a brewing revolt among Tory backbenchers over extending emergency laws. MPs are due to vote next week on a six-month renewal of the Coronavirus Act but an amendment is being tabled by Sir Graham Brady, the chairman of the influential 1992 committee of Conservative backbenchers, intended to secure parliament has a say before any further measures that clamp down on social freedoms. Former interim Labour leader Harriet Harman, the chair of the Parliamentary Labour party, John Cryer, and former deputy chief whip John Spellar were the surprise Labour names among the 46 signatories of the amendment when a list was published on Thursday. Other prominent supporters include former Tory leader Duncan Smith, ex-Brexit secretary David Davis, and former first secretary of state Damian Green. Former minister Steve Baker, who is organising rebels and is among 40 Tory signatories, has claimed he is “100% certain” the amendment will pass if both Labour and the SNP back it too. DUP MPs Ian Paisley Jr and Sammy Wilson are also among opposition signatories of the amendment, which states that ministers ensure “as far as is reasonably practicable that in the exercise of their powers to tackle the pandemic ... Parliament has an opportunity to debate and to vote upon any secondary legislation with effect in the whole of England or the whole United Kingdom before it comes into effect”. The amendment would need support from opposition parties to overcome the government’s 80-seat majority. Discussions are expected to take place in the coming days between Downing Street and rebels, suggesting a deal could be on the cards to avert a Commons showdown on Wednesday. It is understood the text of the amendment has been overseen by a senior clerk, with its supporters confident it will be ruled in order and allowed to proceed to a vote if selected by the Speaker. However, it is thought that the amendment will not actually change the legislation, meaning any government defeat would be symbolic rather than legally binding. Labour has yet to publicly say whether it will back the Brady amendment and the SNP has yet to take a decision. Harman told the Guardian she is planning to table her own amendment designed to ensure new restrictions are put to a vote in parliament within seven days of being introduced, which she says has cross-party support from 37 other MPs. “People recognise that the government is under great time pressure and the virus moves very fast but there’s no excuse for them not to come to parliament, at least within seven days, to get it ratified or indeed come to parliament first,” she said. Harman, who is chair of the joint committee on human rights, made clear the efforts were cross-party and her amendment was not in competition with Brady’s. “The thing is everyone is working together to press the government to recognise that they can’t just keep making and changing the criminal law without any reference to parliament,” she added. The Coronavirus Act 2020 gives the government a wide range of emergency powers to tackle the crisis, although most of the Covid lockdown restrictions – including the rule of six – have been imposed using regulations under the Public Health Act 1984, which take effect prior to a parliamentary vote. However, Tory MPs are seizing on the renewal of the act next week to air their grievances over what many characterise as an assault on basic freedoms. Baker told the Guardian on Thursday: “Members of parliament feel increasingly helpless as measures restricting all of our constituents’ basic civil liberties come into law without our vote on them or even a prior debate. “This amendment is about changing that, taking back control into parliament … Of course, I don’t want to be in the territory of the government losing a vote. What we really want is for the government to reach an accommodation with Sir Graham that will enable us to debate and vote on government measures before they become law. “The idea that we’re all going to go away by being fobbed off with general debates and after the fact votes is for the birds. This is fundamentally a matter of parliamentary democracy and individual liberty, as well as our collective responsibility to one another.” Davis earlier also told the Guardian he was backing the amendment. “It has no power: but if the government ignores it it would be very silly,” he said. “Parliamentary scrutiny is not just about who’s to blame, it’s about improving the quality of the decision-making. Parliament invented crowd-sourcing 200 years ago.” Tory MP Daniel Kawczynski, who is also among the backers, tweeted on Thursday: “Each MP must be accountable for their vote in such a massive civil liberties/economy/jobs/ mental health/issue.” The prime minister’s spokesman said there would be a vote on the renewal of the Coronavirus Act 2020 and that MPs also had the chance to vote on individual regulations, which would lapse within 28 days if MPs decide to vote against them, though they cannot stop them in advance. “It has obviously been important that we can move quickly, particularly in regard to local lockdowns but the current position does provide for parliamentary scrutiny,” the spokesman said.