British MPs will vote Wednesday on a key Brexit bill whose turbulent passage through parliament has dealt damaging defeats to Prime Minister Theresa May, and which still faces stiff opposition in the upper house.
The House of Commons is expected to pass the bill, which will incorporate thousands of pieces of EU legislation into the British statute books and repeal the legislation enshrining Britain's EU membership.
Eleven members of May's Conservative party joined with opposition lawmakers last month to approve an amendment making sure that parliament will have a "meaningful vote" on the final Brexit deal.
Fearful of another loss, the government also compromised on an amendment setting the date and time for Brexit as March 29, 2019, at 2300 GMT.
May agreed to give MPs the "power to amend the definition of 'exit day' to a later date" if it appeared that negotiations would overrun.
The flagship EU (Withdrawal) Bill, if approved, will pass to the upper House of Lords, where it will undergo further scrutiny from the largely pro-EU chamber before being put to another vote.
Veteran Tory MP Kenneth Clarke, a strident europhile, said on Tuesday that the House of Lords could make alterations to the bill.
"The idea that the bill... is going to have an untroubled passage through the House of Lords is an illusion," he said.
"I hope that the other place (Lords) will make an enormous number of changes".
During the first of two days of Commons debate on Tuesday, Conservative MP and leader of the rebellion, Dominic Grieve, raised concerns over plans not to bring the EU charter of fundamental rights into British law post-Brexit.
"It does seem to me that in simply batting this issue away and saying 'don't worry, it's all going to be perfectly all right'... we're sending out a really very strange message about our attitude," he said.
Meanwhile, Scotland's devolved government has repeatedly called for May to accept amendments tabled to prevent devolved powers being removed from its parliament.
After her government again rejected on Tuesday evening proposed changes to the bill, Michael Russell, minister for UK negotiations on Scotland's place in Europe, vowed to press ahead with legislation at Holyrood "if that's what it takes to defend devolution".
Britain and the European Union reached preliminary agreement before Christmas on Britain's financial settlement after Brexit, EU expatriate rights and the future of the Irish border, opening the door to the second phase of talks.
However, May faces a potentially volatile task in establishing what Britain's future relationship with the EU should look like, with some members of her cabinet wanting to stay as close as possible to the single market while others favour a clean break.
European Union leaders on Tuesday even held the door open for Britain to change its mind about ending its four-decade membership.
The comments by EU President Donald Tusk, European Commission Jean-Claude Juncker and others weighed into a debate in Britain about holding a second Brexit referendum.
Leading Brexit campaigner Nigel Farage surprisingly pushed the issue back onto the agenda last week when he said he was increasingly open to the idea of a new vote.
Tusk said: "We on the Continent haven't had a change of heart. Our hearts are still open to you."