British Prime Minister Boris Johnson will try to persuade rebellious lawmakers in his party to vote on Monday for a bill that will break international law by breaching parts of the Brexit divorce deal and which has enraged Brussels.
The House of Commons will debate the Internal Market Bill, which the EU has demanded Johnson scrap by the end of September in the latest brinkmanship of a four-year saga since Britain voted narrowly to leave the bloc.
After the debate, in a vote that may come late, lawmakers will decide if the bill should go to the next stage.
Johnson's plan to explicitly break international law has plunged Brexit back into crisis less than four months before Britain is finally due to leave the EU's orbit at the end of a transition period, and put trade talks with the bloc in peril.
EU diplomats and officials said the bloc could take legal action against Britain, though there would be no resolution before the end-of-year deadline for Britain’s full exit.
The EU has ramped up preparations for a no-deal Brexit, which would be chaotic for business, markets and nearly $1 trillion in annual trade.
The government has dismissed an ultimatum from Brussels to scrap the main parts of the bill by the end of this month.
Johnson, who has a majority of 80 in the lower house of parliament, faces a growing revolt from some of his own lawmakers. All of Britain's living former prime ministers have expressed concern about his plan as have many senior figures in his Conservative Party.
"When the queen’s minister gives his word, on her behalf, it should be axiomatic that he will keep it, even if the consequences are unpalatable," Johnson's former Attorney General Geoffrey Cox said in The Times newspaper.
Cox, who was sacked by Johnson in February, remains an influential figure with colleagues.
The pound fell 3% last week on fears of a no-deal Brexit, but Goldman Sachs said the odds of such a scenario were in fact lower than the market is implying so current sterling levels could be attractive to some investors.
British ministers say the bill, which explicitly states that it could be inconsistent with a host of international laws, is intended to clarify ambiguities - particularly over Northern Ireland - and act as a safeguard in case trade talks fall.
But some EU diplomats say they think London is playing a game of chicken, inviting the collapse of trade talks to either get the deal it wants or leave without a deal.
After former prime ministers John Major, Tony Blair, Gordon Brown and Theresa May scolded Johnson for considering breaking the law, another ex-premier David Cameron also weighed in saying he had "misgivings."
The EU says it cannot trust those who break agreements and that if the bill is not effectively scrapped there will be no trade deal to cover everything from car parts to food.
Irish Foreign Minister Simon Coveney said Johnson's bill was most likely a negotiating tactic and a "thin" free-trade deal was still possible as there were just a few outstanding issues.
If, as expected, it is passed in its second reading on Monday, there will be four more days of debate on the bill's fine print - lasting into Tuesday of next week.
After the vote on Monday, there will be further votes on attempts to change the wording and meaning of the law, and a final vote to decide whether it goes to the next stage. The most crucial vote is likely to take place next week.
If the bill then passes the lower house, it will undergo scrutiny in the House of Lords where opposition from Conservative members is expected to be even stronger. (Reuters)