MPs will vote later on giving Theresa May the power to trigger the start of Britain's divorce talks with the European Union.
After two days of debate that have seen angry Tories hit out at the Government over its exit strategy, the Brexit Bill will enter its final stages in the House of Commons.
But the key vote on Wednesday night is expected to cause more problems for Labour than the Prime Minister as Jeremy Corbyn struggles to contain a revolt in his own ranks.
Some 47 pro-Remain Labour MPs defied the leadership to oppose the European Union (Notification of Withdrawal) Bill at second reading and Mr Corbyn is expected to face a renewed wave of defiance.
The Labour leader is imposing a three-line whip on the vote at the third reading - a move that risks the resignation of high-profile shadow cabinet ministers like Clive Lewis.
Shadow home secretary Diane Abbott, one of Mr Corbyn's closest allies, was widely ridiculed for suffering from a bout of "Brexit flu" after she failed to turn up to vote last week, claiming a migraine.
Three other members of the shadow cabinet, shadow environment secretary Rachael Maskell, shadow Welsh secretary Jo Stevens and shadow equalities minister Dawn Butler, resigned to oppose the Bill.
As well as 10 junior shadow ministers, three whips - enforcers charged with instilling party discipline - also voted against the Bill.
MPs are expected to debate the Bill allowing Article 50 to be triggered for up to seven hours, with the final vote expected to be held at around 8pm.
The Government comfortably defeated attempts on Tuesday night to give MPs a decisive say over the final terms of Brexit, despite anger among Tory remain campaigners.
Seven Conservative MPs, Ken Clarke, Bob Neill, Andrew Tyrie, Claire Perry, Anna Soubry, Antoinette Sandbach and Heidi Allen, defied their party whip.
But their protest was virtually cancelled out by six Labour MPs, Frank Field, Ronnie Campbell, Kate Hoey, Kelvin Hopkins, Graham Stringer and Gisela Stuart, who voted with the Government.
Ms Perry raised eyebrows when she compared hardline Brexiteers to "jihadis" in their relentless pursuit of leaving the EU.
She told MPs: "I have to say that the tone of this debate - and we have heard a little bit, although it is starting to calm down - sometimes borders on the hysterical.
"I feel like sometimes I am sitting along with colleagues who are like jihadis in their support for a hard Brexit."
Tory rebels hit out at the Government after it appeared to make a concession to appease remain campaigners, only to later to play down suggestions it had made any compromise.
Conservative former education secretary Nicky Morgan was seen having a heated exchange with the party's chief whip Gavin Williamson, before returning to the backbenches while the vote took place.
She tweeted: "Govt did make a concession but for No 10 to then brief there was no change & Minister to undermine it makes no sense."
Former minister Mr Neill said he had voted against the Government "for the first time ever".
Ex-chancellor George Osborne failed to turn up for the vote but former minister Nick Boles, who is being treated for a cancerous tumour, left hospital to back the Government in the vote.
The amendment to the European Union (Notification of Withdrawal) Bill required Parliament to approve any new treaty or relationship before final agreement with the EU, but was defeated by 326 votes to 293.
Brexit minister David Jones earlier told MPs there would be a vote on the deal "before it is concluded" and it was intended to take place before the European Parliament debates and votes on the agreement.
Labour claimed the move as a "significant victory" in response to its repeated demands for a "meaningful" vote at the end of the two-year negotiation process.
But pressure group Open Britain said it should be rejected as a "con" and many MPs condemned the refusal to give them a veto should no Brexit deal be agreed.