MPs opposing the government’s EU repeal bill will be voting for a “chaotic” Brexit, ministers have warned.
Brexit Secretary David Davis said people did not “vote for confusion” in last year’s referendum while Foreign Secretary Boris Johnson urged MPs not to “frustrate” the process.
MPs will hold a key vote on the legislation, which aims to end EU law’s supremacy in the UK, on Monday night.
Labour says it will oppose the bill, claiming it represents a “power grab”.
Urging all his MPs to back his position, leader Jeremy Corbyn said he respected the outcome of last year’s Leave vote but said the government was trying to evade parliamentary scrutiny and accrue powers which could put workers rights and environmental safeguards at risk in the future.
The EU (Withdrawal) Bill, which the government previously referred to as the Great Repeal Bill, overturns the 1972 European Communities Act which took the UK into the then European Economic Community.
It will also convert all existing EU laws into domestic ones, to ensure there are no gaps in legislation on Brexit day.
Ministers say this process will ensure a smooth transition out of the EU, avoiding a “cliff-edge of uncertainty”.
But critics say ministers are also handing themselves sweeping powers to change laws without full parliamentary scrutiny.
Justice Minister Dominic Raab promised a “sensible conversation” over the use of so-called delegated powers, which the government says are needed to make minor tweaks to legislation to ensure the Brexit process runs smoothly.
Mr Raab said most of the bill would be subject to “maximum scrutiny”, telling Sky News: “This idea that there’s going to be no scrutiny or no accountability is just wrong.”
Former Conservative Chancellor Ken Clarke predicted the government would have to change the wording of the bill to deal with concerns about what he said was an unprecedented use of delegated powers.
A taste of things to come
BBC political editor Laura Kuenssberg
Ministers accept privately that they will probably have to budge in some areas. But tonight’s midnight vote is not likely to be the big showdown.
Tory rebels will, in the main, vote for the bill in principle, and enter hand-to-hand combat in the more detailed stages in the next couple of months. And although the opposition will vote against the bill this evening, there are also anxious MPs on that side of the House of Commons who won’t, worried about appearing to be blocking Brexit by “killing the bill”.
But tonight will be the first real taste of the months to come, the House of Commons sitting until midnight, the government anxiously totting up the numbers, MPs being told to cancel any plans they have to be around for vital votes.
Read Laura’s blog
Labour, which says the bill will give the government powers similar to those used by medieval monarchs, has tabled a series of amendments and will order its MPs to oppose it at second reading stage unless its changes are accepted.
“I hope Labour MPs will recognise that Labour fought the election recognising the result of the referendum… and that we would seek parliamentary scrutiny of the whole negotiating process,” Mr Corbyn told BBC Radio 4’s World at One.
“It does not mean handing over all our decision-making on how the negotiations proceed to one secretary of state. This is a power grab by the government at the expense of our democratically elected Parliament.”
But Labour MP Caroline Flint, a former minister for Europe, is refusing to vote against the bill despite the three-line whip imposed by her party – the strongest available sanction.
“Our job is to improve this bill,” she told BBC Radio 4’s Today programme. “Not kill it at birth.”
Ms Flint, who has yet to defy the whip, said voting the bill down would cause “huge problems” by ending the session of Parliament and requiring an entirely new bill.
“There are MPs on all sides of the House [of Commons] including on the government’s side who feel this bill could be improved,” she added.
The SNP and Liberal Democrats also plan to vote against the bill but the government has the support of the Democratic Unionist Party, with whom they have a deal to secure a Commons majority.
The Lib Dems said the chances of inflicting a government defeat lay with Labour MPs following Jeremy Corbyn’s instruction to oppose the bill, and urged him to sack any frontbenchers who defied his orders.
Foreign Secretary Boris Johnson said passing the bill was an important step in “honouring the promises” the government had made to the British people regarding Brexit and ensuring the referendum result was “vindicated”.
“We need to get this great ship launched,” he told BBC Radio 4’s Today.
“I do very much hope we will win tonight but people who vote against it will be effectively voting to frustrate Brexit by producing a completely chaotic result.”
And Mr Davis said the measures in the bill would mean the UK could leave the EU “safe in the knowledge that we are ready for day one of exit”.
“A vote against this bill is a vote for a chaotic exit from the European Union,” he warned. “The British people did not vote for confusion and neither should Parliament. Without it, we would be approaching a cliff edge of uncertainty which is not in the interest of anyone.”
MPs are also expected to vote on the timetable for line-by-line consideration of the bill, with debate expected to continue late into the night.