Saturday's Brexit votes in Parliament: What's going on and what time is the vote?
Saturday's Brexit vote in Parliament: What happens now?
(32 minutes later)
Parliament is sitting on a Saturday for the first time in 37 years to debate and vote on Boris Johnson's Brexit deal - here is what to expect.
Parliament has been sitting on a Saturday for the first time in 37 years to debate and vote on Boris Johnson's Brexit deal.
What is happening?
What just happened?
MPs began their special session at just after 09:30 BST.
MPs have supported a motion tabled by Independent MP Sir Oliver Letwin that "withholds approval" for Boris Johnson's Brexit deal until legislation implementing it has been passed.
Peers started their debate at 10:00 and are due to finish at 15:00.
It was very close - the government lost by just 16 votes, by 322 to 306.
Commons proceedings got under way with a statement from Prime Minister Boris Johnson and a response from Labour leader Jeremy Corbyn.
It was due to be followed by a vote on the main government motion - whether or not to back the deal. But the motion, as amended, was approved by MPs without a vote, as the government effectively accepted defeat.
The prime minister took questions on his Brexit deal from MPs for nearly two hours and this was followed by a debate. They have finished the debate and are now voting.
A vote on a cross-party amendment on preventing a no-deal referendum and holding a second referendum was dropped.
What time will voting get under way?
What happens now?
The voting has now started.
Under the terms of the so-called Benn Act, the prime minister must send a letter to Brussels requesting a three month Brexit delay by midnight.
There could be up to four votes.
But Prime Minister Boris Johnson said: "I will not negotiate a delay with the EU and neither does the law compel me to do so."
Commons Speaker John Bercow has selected two amendments to be voted on by MPs.
He added: "I continue in the very strong belief that the best thing for the UK, and for the whole of Europe is for us to leave with this new deal on 31 October, and to anticipate the questions that are coming from the benches opposite, I will not negotiate a delay with the EU."
They are:
A Number 10 source said: "Parliament has voted to delay Brexit yet again.
The first vote is on the Letwin amendment - it could turn out to be the only vote taken on Saturday.
"The prime minister will not ask for an extension - he will tell EU leaders there should be no delays, they should reject Parliament's letter asking for a delay, and we should get Brexit done on 31 October with our new deal so the country can move on."
It was due to be followed by a vote on the main government motion - whether or not to back the deal.
The House of Commons Twitter account posted that the government now "must ask for an extension of Article 50 under the Benn Act and set out how it intends to proceed".
But the government does not want this vote to happen if MPs back the Letwin amendment, as it could delay Brexit.
What have opposition parties said?
It is not clear at this stage how they would prevent the vote happening - it's possible Tory MPs could decline to take part and will be sent home by party managers.
Labour leader Jeremy Corbyn told MPs: "Today is an historic day for parliament because it said it will not be blackmailed by a prime minister who is apparently prepared once again to defy a law passed by this parliament.
But the motion has already been tabled and the government can not "pull" the vote on it.
"I invite him to think very carefully about the remarks he just made about refusing, apparently, to apply for the extension which the EU number two Act requires him to do."
Downing Street says that even if MPs back the main government motion, with the Letwin amendment, it could not be seen as a vote in favour of a deal, because the amendment says: "This House has considered the matter but withholds approval unless and until implementing legislation is passed."
SNP justice and home affairs spokesperson Joanna Cherry tweeted: "So Boris Johnson loses again today but is threatening not to comply with BennAct or promises made to Scottish court.
If the vote on the Brexit deal does take place, and MPs reject it, we could then move to votes on a second government motion on whether or not there should be a no-deal Brexit.
"Just as well we are due back in court on Monday & Mr Speaker has just confirmed to me that he'll sign Extension letter if court so requires."
Before a vote takes place on that, MPs could get a chance to vote on the cross-party amendment rejecting a no-deal Brexit and seeking another referendum.
Is Boris Johnson's deal now dead?
MPs would then vote for a fourth time - on the government no-deal motion. We know there is a majority in the Commons against a no-deal Brexit, so this would be unlikely to pass.
No. The government now plans to push ahead with the legislation enacting the treaty agreed by Boris Johnson in Brussels - the Withdrawal Agreement Bill.
What happens if the Letwin amendment passes?
It means a deal will not have been approved by 2300 so, under the terms of the Benn Act, the prime minister must send a letter to Brussels requesting a three month Brexit delay.
But regardless of what happens on Saturday, the government has said it plans to push ahead with the legislation enacting the treaty agreed by Boris Johnson in Brussels - the Withdrawal Agreement Bill.
They plan to hold the second reading of that bill on Tuesday, which would give MPs a chance to register their support - or not - for Boris Johnson's Brexit deal.
They plan to hold the second reading of that bill on Tuesday, which would give MPs a chance to register their support - or not - for Boris Johnson's Brexit deal.
What happens if MPs vote for the deal?
If the government motion is passed by MPs without being amended, it will just be the first stage of getting the deal into law.
The government is likely to want to move quickly so it can meet Boris Johnson's 31 October deadline.
The Withdrawal Amendment Bill, which implements the legally-binding treaty, will be presented to Parliament early next week - something the government now plans to do whatever happens in Parliament on Saturday.
How can you follow the debate?
You can find out the latest developments on the BBC News website and app, where we'll have live coverage in text and video, and analysis from our experts.
There will also be coverage on BBC Two from 13:15 to 16:30, and continuous coverage on the BBC News Channel.
There will also be extended editions of BBC News at Six and News at Ten, as well as a special edition of BBC Newsnight.
Why is the Letwin amendment significant?
By the BBC's Parliamentary Correspondent Mark D'Arcy
The government seems to be all but conceding that the Letwin amendment will pass, and is making its dispositions accordingly - announcing plans to hold a "meaningful vote" on the Withdrawal Agreement Bill on Tuesday.
This would corner MPs into a Yes/No vote on their deal, and given there are a fair number of Labour rebels, the government could well win.
Certainly, the vote would put any number of Labour MPs - and MPs for other parties - from Brexit-voting constituencies in a very awkward place.
Watch out for an attempt to attach a second referendum to the deal in some way.
But the success of that effort would require full-throated support (and whipping of their MPs) from the Labour Party. They are not there yet, and they may never be.
If the government wins a "meaningful vote" on Tuesday, the legislation to underpin the new deal would then go forward - and that would provide further opportunities to attempt amendments.
Winning the next meaningful vote is only the beginning of a new phase of Brexit; it's not even the beginning of the end.
