Update 4 (2:35AMET): After getting off to a strong start with a wide margin of victory for the second reading of the withdrawal bill, Johnson has lost the critical motion program, 308-322.

That means Johnson's plan to fast-track the passage of his withdrawal agreement bill has been defeated, meaning he will rely on Brussels to approve a brief extension to pass his withdrawal plan during a more "reasonable timetable."

Though the pound plunged, Johnson sounded optimistic in his post-vote remarks, noting the significance of the fact that Parliament has finally voted in favor of a Brexit deal for the first time.

The news appears to be hurting stocks across the water...

In his post-vote remarks, Johnson said the Tories would now 'pause' their legislation until the EU answers Johnson's request for another Brexit delay.

According to BBG, if the EU grants an extension of one week, or two, Johnson will likely press on with his bill, but on a more relaxed timetable. However, should MPs insist on a delay for 3 months, then we're likely headed for elections.

But as Speaker John Bercow clarified during the post-vote debates, the Brexit deal itself has, for the first time, won a majority of votes in the Commons. Since the program motion was defeated, according to Bercow, Johnson will be forced to "pause and consider how to proceed".

However, in a comment that undoubtedly annoyed Johnson, jhk

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Update 3 (2:15PMET): The vote on the second reading is over, and though the DUP are opposing Johnson's withdrawal agreement with the EU, a larger number of opposition MPs than anticipated sided with Johnson, delivering him his first win in what's expected to be a series of whirlwind votes.

The final total: 329-299.

Next up: The biggest vote of the day on whether to support Johnson's 'program motion' - whether to fast-track the Brexit Withdrawal Agreement Bill.

Though the successful vote on the second reading of Johnson's Withdrawal Agreement Bill - or 'WAB', for short - might seem like an obscure technicality, the ramifications of this vote are quite profound: Not only is this the first time that Parliament has supported an official Brexit plan, the vote also passed by a 30-point margin, which was larger than anticipated.

The pound has rallied to its highest level of the day in response.

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Update 2 (11:35AMET): Amid a nail-biting session that has left currency traders chewing their nails with anticipation, the pound climbed in mid-morning (Eastern Time) US trade

The cause for the jump? Rumors that Johnson might acquiesce to one more delay instead of taking the 'my way or the high way' approach. i

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Update (0845ET) : Cable is sliding after The BBC reports that a source at No.10 says "if Parliament votes again for delay by voting down the programme motion, and the EU offers delay until 31 Jan -- then we will pull the Bill, there will be no further business for Parliament and we'll move to an election before Christmas"

Statista offers a simplistic flowchart of what happens next...

You will find more infographics at Statista

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As we detailed earlier, after being twice stymied by the opposition during Saturday's historic session and again on Monday, UK Prime Minister Boris Johnson is facing the beginning of an accelerated series of votes with the ultimate goal of pushing his withdrawal agreement through the House of Commons this week, which would ensure that the UK leaves the EU at the end of the month.

However, some of the MPs who ostensibly support his Brexit deal apparently have reservations about this three-day "whirlwind" timetable. According to the Times of London, Johnson has been warned that his attempt to kick off the votes on the Withdrawal Agreement Bill Tuesday night will be met with defeat unless he agrees to a longer post-Brexit transition.

Nick Boles, a member of the group of Tory rebels who left the party last month, has proposed an amendment to extend the Brexit transition period until the end of 2022 unless MPs pass a resolution to cut it short.

Last night, Johnson's government officially published the "withdrawal agreement bill" for its first reading (of three). That bill is likely to pass its first vote on Tuesday (the "second reading" vote) thanks to the support of expelled former Tories and opposition rebels, despite confusion over Labour’s official stance on the second reading. Another vote on Tuesday over whether to approve the express timetable for the WAB (withdrawal agreement bill) could derail the prime minister’s Brexit dash, as several former Tory rebels have warned that they want to slow down the process to ensure the "proper scrutiny" is applied.

Rory Stewart, a former Tory who was expelled from the party last month, warned against ramming the bill through Parliament, arguing that it might "further undermine confidence in our institutions."

"That means delivering a deal with proper process and scrutiny. Ramming through the bill will further undermine confidence in our institutions. We must do this properly."

If the program motion - the technical term for the vote on whether to accelerate the process of passing the withdrawal agreement bill - fails, it will virtually ensure that the UK doesn't complete the Brexit process at the end of the month. The EU has so far held off on granting an official extension, since it's waiting on developments in Westminster.

The Tory whip has warned that the vote on the program motion will be tight, and that Johnson will need to pick up 20 opposition votes to offset votes from former conservatives.

However, since most sell-side research shops and the FT's vote tracker now believe Johnson has the votes to ultimately pass his Brexit deal - even without the support of the DUP and its 10 MPs - it's widely expected that any Brexit delay from this point onward would likely be brief. However, Johnson has reportedly warned MPs that he would abandon the bill if MPs force through amendments that are outside the scope of the deal with the EU. Opponents of Johnson's deal have also warned that they might attempt to amend it as it goes through the committee stage.

Of course, that could swiftly leave the UK in caretaker government/election territory, as analysts at DB warn.

Also, thanks to the transition period, Britain won't actually finish with the business of leaving the EU until the end of next year.

Johnson hopes to pass the WAB by end of day Thursday, giving the House of Lords a chance to vote on Friday.

Since Johnson is facing a punishing gauntlet of votes, yields on eurozone bonds dropped on Tuesday morning, reflecting the market's anxieties as the deadline approaches. The pound was also weakening early in the day in New York.

Here's a schedule of upcoming Commons votes (courtesy of DB):

Tuesday 12.30 p.m.: Second Reading debate starts 7 p.m.: Vote on Second Reading - the general principle of the bill 7.15 p.m.: Vote on Program Motion - the timetable for the rest of the bill’s passage 7.30 p.m.: (If Program Motion passes) Committee Stage begins 10.30 p.m.: First Committee Stage votes Wednesday After 12.30 p.m.: Committee Stage continues, with votes every three hours. Amendments on keeping the U.K. in a customs union with the EU and calling a second referendum are likely to appear After Midnight: Committee Stage finishes Thursday After 11 a.m.: Report Stage begins. More amendments can still be proposed After 5 p.m.: Report Stage votes After 7 p.m.: Third Reading vote - the House of Commons’s final say on the bill

Ultimately, both the FT's vote-tracker and most sell-side research shops expect the a final vote on the withdrawal agreement to pass by a moderate margin.