Labour leader Jeremy Corbyn says his party will support an early general election as the government makes its pitch for a poll on 12 December.
Mr Corbyn said his condition of taking a no-deal Brexit off the table had "now been met" after the EU agreed to extend the deadline to 31 January 2020.
Shadow justice secretary Richard Burgon said Labour wanted Boris Johnson "out before Christmas", but did not confirm his party's preferred poll date.
MPs will vote on timings later.
The SNP and Liberal Democrats want a 9 December poll, saying it would prevent the prime minister from pushing his Brexit deal through Parliament.
The government bill published ahead of the Commons debate is for an early election on 12 December.
But No 10 sources have told the BBC they would accept 11 December to get opposition parties on-board.
Mr Corbyn told his shadow cabinet: "I have consistently said that we are ready for an election and our support is subject to a no-deal Brexit being off the table.
"We have now heard from the EU that the extension of Article 50 to 31 January has been confirmed, so for the next three months, our condition of taking no-deal off the table has now been met.
"We will now launch the most ambitious and radical campaign for real change our country has ever seen."
Mr Burgon said Labour would be pushing to get votes for 16 and 17-year-olds, as well as EU nationals so they can have their say.
But he added: "Even if we don't get those things we want, when push comes to shove, we are going to support an election."
An infectious disease that can harm the brain and is spread to people by tick bites has been identified in ticks in the UK for the first time.
Public Health England (PHE) says it has confirmed cases of tick-borne encephalitis virus in ticks from two parts of England - Thetford Forest and an area on the Hampshire-Dorset border.
PHE says the risk to people is still "very low".
It is monitoring the situation to check how common the infected ticks may be.
What is it?
A tick is a tiny, spider-like creature that lives in undergrowth and on animals, including deer and dogs.
People who spend time walking in countryside areas where infected ticks can be found are at risk of being bitten and catching diseases they carry.
Tick-borne encephalitis virus is already circulating in mainland Europe and Scandinavia, as well as Asia.
Evidence now shows it has reached the UK.
How it got here is less clear. Experts say infected ticks may have hitched a ride on migratory birds.
Earlier this year, a European visitor, who has since recovered, became ill after being bitten by a tick while in the New Forest area, Public Health England says.
Further investigations revealed infected ticks were present in two locations in England.
Should I worry?
Ticks are becoming more common across many parts of the UK, largely due to increasing deer numbers. Being bitten by one doesn't necessarily mean you will get sick.
Dr Nick Phin, from Public Health England, said: ''These are early research findings and indicate the need for further work. However, the risk to the general public is currently assessed to be very low."
Most people who catch the virus will have no or only mild flu-like symptoms. But the disease can progress to affect the brain and central nervous system and can sometimes be fatal.
Ticks can also carry other diseases that can make people ill including Lyme disease.
Dr Phin said: "We are reminding people to be 'tick aware' and take tick precautions, particularly when visiting or working in areas with long grass such as woodlands, moorlands and parks."
What should I do?
To reduce the risk of being bitten, cover your skin, tuck your trousers into your socks, use insect repellent and stick to paths
If you are bitten, remove the tick with fine-tipped tweezers or a tick-removal tool found in chemists
Clean the bite with antiseptic or soap and water
You should go to your GP if you think you may have been bitten by a tick in the past month and develop flu-like symptoms or a circular red rash
Ticks feed on the blood of animals and people.
They cannot jump or fly but live in vegetation and wait for a passing animal or human to climb on to.
An infectious disease that can harm the brain and is spread to people by tick bites has been identified in ticks in the UK for the first time.
Public Health England (PHE) says it has confirmed cases of tick-borne encephalitis virus in ticks from two parts of England - Thetford Forest and an area on the Hampshire-Dorset border.
PHE says the risk to people is still "very low".
It is monitoring the situation to check how common the infected ticks may be.
What is it?
A tick is a tiny, spider-like creature that lives in undergrowth and on animals, including deer and dogs.
People who spend time walking in countryside areas where infected ticks can be found are at risk of being bitten and catching diseases they carry.
Tick-borne encephalitis virus is already circulating in mainland Europe and Scandinavia, as well as Asia.
Evidence now shows it has reached the UK.
How it got here is less clear. Experts say infected ticks may have hitched a ride on migratory birds.
Earlier this year, a European visitor, who has since recovered, became ill after being bitten by a tick while in the New Forest area, Public Health England says.
Further investigations revealed infected ticks were present in two locations in England.
Should I worry?
Ticks are becoming more common across many parts of the UK, largely due to increasing deer numbers. Being bitten by one doesn't necessarily mean you will get sick.
Dr Nick Phin, from Public Health England, said: ''These are early research findings and indicate the need for further work. However, the risk to the general public is currently assessed to be very low."
Most people who catch the virus will have no or only mild flu-like symptoms. But the disease can progress to affect the brain and central nervous system and can sometimes be fatal.
Ticks can also carry other diseases that can make people ill including Lyme disease.
Dr Phin said: "We are reminding people to be 'tick aware' and take tick precautions, particularly when visiting or working in areas with long grass such as woodlands, moorlands and parks."
What should I do?
To reduce the risk of being bitten, cover your skin, tuck your trousers into your socks, use insect repellent and stick to paths
If you are bitten, remove the tick with fine-tipped tweezers or a tick-removal tool found in chemists
Clean the bite with antiseptic or soap and water
You should go to your GP if you think you may have been bitten by a tick in the past month and develop flu-like symptoms or a circular red rash
Ticks feed on the blood of animals and people.
They cannot jump or fly but live in vegetation and wait for a passing animal or human to climb on to.
EU leaders have agreed in principle to extend Brexit until 31 January 2020 - meaning the UK will not leave as planned on Thursday.
EU Council President Donald Tusk said it was a "flextension" - meaning the UK could leave before the deadline if a deal was approved by Parliament.
It comes as MPs prepare to vote on proposals by Boris Johnson for an early general election on 12 December.
The SNP and Lib Dems have also proposed an election on 9 December.
The government has not ruled out getting behind that proposal date, if it fails to get its preferred date through the Commons later.
The UK was due to leave the EU on Thursday, but Mr Johnson was required to request an extension after Parliament failed to agree a Brexit deal.
The prime minister had repeatedly said the UK would leave on 31 October deadline with or without a deal, but the law - known as the Benn Act - requires him to accept the EU's extension offer.
The president of the European Parliament, David Sassoli, said the extension was "positive", and "gives time for the UK to make clear what it wants".
Boris Johnson's "do or die" pledge to leave by 31 October is no more - it is dead.
Many will see this as a no-deal Brexit being taken off the table, at least until 31 January.
So it will increase the arguments in the Commons that with no-deal parked, Parliament now has to make a decision on an election.
And that is what Mr Johnson will be trying to argue over the next few days.
For the PM, there is a risk of calling an election without Brexit being resolved, as he may be punished for it at the ballot box.
So, while it buys more time, it also creates an element of uncertainty for the prime minister.
He will now campaign for an election in the knowledge that he has failed in his signature policy which he campaigned for in the Conservative leadership election.
Mr Tusk will now seek the UK's formal agreement to the decision, before formalising the extension through a written procedure among the 27 other EU nations.
An EU official said they hoped for the process to be concluded by Tuesday or Wednesday.
MPs are due to vote on the prime minister's election call after 17:00 GMT.
Mr Johnson said if Parliament agreed to an election on 12 December, he would restart efforts to get his Withdrawal Agreement Bill - the legislation enacting the Brexit deal he struck with Brussels - into law.
The bill passed its first hurdle last week after MPs backed it at the second reading by a majority of 30.
But minutes later they voted against a timetable that would see it pass through Parliament in just three days, so the PM "paused" its progress.
Labour has repeatedly said it will not back an early general election until a no-deal Brexit is taken off the table.
The party was predicted to abstain in Monday's vote, effectively killing off the government's plans.
The SNP also said it would block the government's election attempt.
But it has broken with the Labour position and joined forces with the Liberal Democrats to push for an election on 9 December, provided there is an extension.
The SNP and Lib Dems have proposed a bill that would tweak the Fixed-term Parliaments Act 2011 - the law which sets the time-frame for elections.
If passed, it would enable an election to take place with only a majority of one, rather than two-thirds of MPs.
It is confirmed by the EU that we will not be leaving on the 31st Oct @BorisJohnson has failed to take us off the cliff edge, he has been defeated again. Let us have the election @thesnp will do its job and put across our message that those in Scotland should decide our future
Asked about the Lib Dem/SNP proposal, Education Secretary Gavin Williamson said the government would "always look at every single option".
But he told BBC Breakfast: "The best way is to vote for the motion tonight. This Parliament is totally broken. Let the people decide the next step forward."
MPs have already twice rejected a call from the PM to hold a general election.
EU leaders have agreed in principle to extend Brexit until 31 January 2020 - meaning the UK will not leave as planned on Thursday.
EU Council President Donald Tusk said it was a "flextension" - meaning the UK could leave before the deadline if a deal was approved by Parliament.
It comes as MPs prepare to vote on proposals by Boris Johnson for an early general election on 12 December.
The SNP and Lib Dems have also proposed an election on 9 December.
The government has not ruled out getting behind that proposal date, if it fails to get its preferred date through the Commons later.
The UK was due to leave the EU on Thursday, but Mr Johnson was required to request an extension after Parliament failed to agree a Brexit deal.
The prime minister had repeatedly said the UK would leave on 31 October deadline with or without a deal, but the law - known as the Benn Act - requires him to accept the EU's extension offer.
Boris Johnson's "do or die" pledge to leave by 31 October is no more - it is dead.
Many will see this as a no-deal Brexit being taken off the table, at least until 31 January.
So it will increase the arguments in the Commons that with no-deal parked, Parliament now has to make a decision on an election.
And that is what Mr Johnson will be trying to argue over the next few days.
For the PM, there is a risk of calling an election without Brexit being resolved, as he may be punished for it at the ballot box.
So, while it buys more time, it also creates an element uncertainty for the prime minister.
He will now campaign for an election in the knowledge that he has failed in his signature policy which he campaigned for in the Conservative leadership election.
Mr Tusk will now seek the UK's formal agreement to the decision, before formalising the extension through a written procedure among the 27 other EU nations.
An EU official said they hoped for the process to be concluded by Tuesday or Wednesday.
MPs are due to vote on the prime minister's election call after 17:00 GMT.
Mr Johnson said if Parliament agreed to an election on 12 December, he would restart efforts to get his Withdrawal Agreement Bill - the legislation enacting the Brexit deal he struck with Brussels - into law.
The bill passed its first hurdle last week after MPs backed it at the second reading by a majority of 30.
But minutes later they voted against a timetable that would see it pass through Parliament in just three days, so the PM "paused" its progress.
Labour has repeatedly said it will not back an early general election until a no-deal Brexit is taken off the table.
The party was predicted to abstain in Monday's vote, effectively killing off the government's plans.
The SNP also said it would block the government's election attempt.
But it has broken with the Labour position and joined forces with the Liberal Democrats to push for an election on 9 December, provided there is an extension.
The SNP and Lib Dems have proposed a bill that would tweak the Fixed-term Parliaments Act 2011 - the law which sets the time-frame for elections.
If passed, it would enable an election to take place with only a majority of one, rather than two-thirds of MPs.
It is confirmed by the EU that we will not be leaving on the 31st Oct @BorisJohnson has failed to take us off the cliff edge, he has been defeated again. Let us have the election @thesnp will do its job and put across our message that those in Scotland should decide our future
Asked about the Lib Dem/SNP proposal, Education Secretary Gavin Williamson said the government would "always look at every single option".
But he told BBC Breakfast: "The best way is to vote for the motion tonight. This Parliament is totally broken. Let the people decide the next step forward."
MPs have already twice rejected a call from the PM to hold a general election.
EU leaders have agreed in principle to extend Brexit until 31 January 2020 - meaning the UK will not leave as planned on Thursday.
EU Council President Donald Tusk said it was a "flextension" - meaning the UK could leave before the deadline if a deal was approved by Parliament.
It comes as MPs prepare to vote on proposals by Boris Johnson for an early general election on 12 December.
The SNP and Lib Dems have also proposed an election on 9 December.
The government has not ruled out getting behind that proposed date, if, as expected, it fails to get its preferred date through the Commons later.
The UK was due to leave the EU on Thursday, but Mr Johnson was required to request an extension after Parliament failed to agree a Brexit deal.
Boris Johnson had repeatedly said the UK would leave on 31 October deadline "do or die", but the law - known as the Benn act - also requires him to accept the offer.
Mr Tusk will now seek the UK's formal agreement to the decision - before formalising the extension through a written procedure among the 27 other EU nations, which he hopes to conclude by Tuesday or Wednesday.
The BBC's assistant Political Editor Norman Smith said the decision saw a no-deal Brexit taken off the table - which will increase the pressure on MPs to decide on a general election.
MPs are due to vote on the prime minister's election call after 17:00 GMT.
Mr Johnson said if Parliament agreed to the vote, he would bring back his Withdrawal Agreement Bill for MPs to scrutinise.
The bill passed its first hurdle last week after MPs backed it at the second reading by a majority of 30.
But minutes later they voted against a timetable that would see it pass through Parliament in just three days, so the PM "paused" its progress.
MPs are due to vote later on Boris Johnson's call to have an election on 12 December.
The prime minister says he will restart moves to get his Brexit deal bill into law if the motion is passed.
But he looks unlikely to get the support of the two-thirds of MPs he needs by law to agree to an election, with opposition parties against it.
The UK is due to leave the EU on Thursday, but the bloc is considering an extension to that date.
They agreed to delay Brexit in principle last week, but EU ambassadors are meeting again this morning, with BBC Brussels reporter Adam Fleming saying there were "high hopes" of a final decision.
A draft text of an agreement for the 27 ambassadors includes multiple possible dates for Brexit - 30 November, 31 December or 31 January - and an option for the UK to leave earlier if and when a deal is signed off.
There will also be a commitment that the Withdrawal Agreement on the UK's exit from the EU cannot be renegotiated in future.
Adam Fleming said if the ambassadors and the UK agreed, the extension process could completed in writing without the leaders of each of the EU states needing to be present.
Vote for a vote
In Westminster, MPs are due to vote on the prime minister's election call after 17:00 GMT.
Labour leader Jeremy Corbyn said his party is not prepared to support it until a no-deal Brexit is ruled out, with his party's MPs expected to abstain in the vote.
The SNP has also said it will block the government's election attempt.
But the party has joined forces with the Liberal Democrats to push for an election on 9 December - provided the EU grants a Brexit extension until 31 January.
They have proposed a bill which would tweak the Fixed-term Parliaments Act 2011 - the law which sets the time-frame for elections - and enable a poll to take place with only a simple majority of MPs voting for it, rather than two-thirds of MPs.
Lib Dem leader Jo Swinson said she wanted to stop Mr Johnson from "ramming through his Brexit bill".
She told BBC Radio 4's Today programme setting the date in law would also remove any "wriggle room" the PM had around his own proposals.
Ms Swinson said she had written to the prime minister but was yet to get a response.
Asked about the Lib Dem/SNP proposal, Education Secretary Gavin Williamson said the government would "always look at every single option".
But he told BBC Breakfast: "The best way is to vote for the motion tonight. This Parliament is totally broken. Let the people decide the next step forward."
Labour's Lucy Powell also criticised the SNP/Lib Dem plan.
"What we've seen from the Liberal Democrats and the SNP is trying to shape the terms of that election in a way that would favour them the most. It's pure playing of politics," she told BBC Radio 4's Westminster Hour.
MPs have already twice rejected a call from the PM to hold a general election.
Mr Johnson has sent a letter to the EU requesting a Brexit delay until 31 January. He was compelled to do so by a law passed by MPs - known as the Benn Act.
Before this, the prime minister repeatedly insisted the UK would leave the EU on 31 October, with or without a deal.
The decision by the Lib Dems and SNP is basically to abandon a "People's Vote" in this Parliament and to campaign now for a general election.
That is the only way, they believe, that you can change the maths in Parliament to make a People's Vote more likely.
It points to the break-up of the so-called Rebel Alliance, which has hung together through thick and thin and has stymied Mr Johnson.
The Lib Dems and the SNP appear to be moving in on one direction - and Labour and the Greens in the other.
