More than 400 amendments have been tabled to the EU Withdrawal Bill, which is created to convert EU law into United Kingdom legislation by the end of March 2019.
Parliament is involved in a lively debate as the Government seeks to enshrine the Brexit date into United Kingdom law.
Ex-chancellor Ken Clarke - who was afforded rare applause in the House of Commons by Labour MPs at one point during Tuesday's debate - branded the Government amendment "ridiculous and unnecessary", adding: "It could be positively harmful to the national interest".
As MPs debated the EU Withdrawal Bill, the Prime Minister met with Scottish First Minister Nicola Sturgeon in Downing Street.
Media captionWhat's going on with the EU Withdrawal Bill?
However, Brexit secretary David Davis conceded that even if MPs failed to back that legislation - the withdrawal agreement and implementation bill, Britain would still leave the European Union on March 29, 2019.
The bill - also known as the Repeal Bill - is meant to ensure legal certainty and avoid a damaging "cliff-edge" when Britain leaves the bloc.
The Telegraph claimed at least 15 Tory MPs are ready to side with Labour and fight against the date of Brexit being enshrined in law.
Some of his colleagues, including former cabinet minister Morgan, shouted "you won't be", indicating they would join him in rejecting the timetable. If I wanted to do that, I would not have supported Article 50.
A vote on that amendment was expected late Tuesday.
Two Cabinet members quit in the past fortnight - defence secretary Sir Michael Fallon and worldwide development secretary Priti Patel - while two others stand accused of instructing May how to run Brexit.
The EU (Withdrawal) Bill is a key part of the government's strategy for leaving the EU following last year's referendum.
May is also under increasing pressure from Brussels to come up with a financial offer to keep negotiations on track, with a crunch summit of European Union leaders looming in mid-December.
A spokeswoman for May s office said the prime minister stressed that as powers were repatriated from Brussels back to Britain, a significant number would be passed down to the devolved administrations in Scotland, Wales and Northern Ireland.
"We oppose Brexit but we understand withdrawal legislation is necessary, so we want to find agreement", Sturgeon said after talks with May.