Could there be an early general election?
A vote on the Queen's Speech is among a number of possible triggers for an early general election.
But how soon could an election happen and why does Prime Minister Boris Johnson want one?
Why does Boris Johnson want an early election?
The next election isn't due until 2022 - but the PM wants an early election to try to restore the Conservative Party's ruling majority in the Commons.
At the moment, if every opposition MP voted against the government, it would lose by 45 votes.
But while calling an early election carries risks, Mr Johnson would hope to end the political stalemate and make it easier to deliver Brexit.
How quickly can an election happen?
Once an election is called, there has to be a gap of at least five weeks before polling day.
That's because the law requires Parliament to dissolve 25 working days before the election.
At this point, politicians stop being MPs and campaign for re-election, if they choose to stand again.
Traditionally, UK elections are held on a Thursday. So, if an election was triggered in the week beginning Monday 21 October, the earliest date the poll could take place is Thursday 28 November.
Why hasn't an election already been called?
In September, the prime minister twice challenged MPs to hold an early election - only to be rejected both times.
Mr Johnson can't just decide to hold an early election. He needs the support of two-thirds of MPs - at least 434. This is a legal requirement, set out under the Fixed-term Parliaments Act (FTPA).
Opposition parties said they would not agree to an early election while there was still a possibility of a no-deal Brexit on 31 October. They said they didn't trust the PM to stick to a pledge to hold an election beforehand.
Will the outcome of the Brexit talks lead to an election?
Should the prime minister fail to reach a deal with the EU by 19 October- or persuade MPs to support one that is agreed - a law called the Benn Act comes into play. If Mr Johnson complies, he must ask for a Brexit extension into the new year.
It is possible that this would see more MPs back a call for an early election.
What role could the Queen's Speech play?
A Queen's Speech - which provides the government with an opportunity to highlight its forthcoming priorities - is due on 14 October.
MPs will then debate its contents, followed by a vote, which is usually held four or five days later.
It's extremely rare for a government to lose a Queen's Speech vote, but Mr Johnson goes into it off the back of seven Commons defeats.
By voting against the Queen's Speech, MPs would be rejecting Mr Johnson's programme for government.
This would lead to pressure on all parties to back an early election. This could happen in a number of ways.
A vote under the Fixed-term Parliaments Act
After a Queen's Speech defeat, the government could once again ask MPs to support an early election.
However, another vote under the Fixed-term Parliaments Act would still require at least two-thirds of MPs to agree.
Bypass the Fixed-term Parliaments Act
If the government felt it couldn't reach the two-thirds threshold, it may try to get round the requirement altogether.
It could do so by introducing a very short law that calls for an election and adds "notwithstanding the Fixed-term Parliaments Act".
The advantage of this route - from the government's point of view - is that it would only require a simple majority of MPs to support it rather than two-thirds.
But it would also need to clear all stages in the House of Commons and the House of Lords. That means there's a risk the law could be sabotaged if MPs or peers propose changes to the wording.
Labour calls a motion of no confidence
Labour could choose to hold a no-confidence vote.
This would give all MPs a vote on whether they wanted the current government to continue. Only a simple majority would be needed.
If it succeeded, opposition parties would be allowed two weeks to come together to try to form an alternative government. If this happened, Mr Johnson would be expected to resign and a new prime minister would take over.
But if nothing was resolved during those two weeks, the FTPA says a general election would be automatically triggered.
Under this scenario, an election would take place at least seven weeks after a no-confidence vote was passed. That's because two weeks would be taken up by opposition parties trying to form a government, plus a further five weeks to dissolve Parliament for the campaign.
Government calls a motion of no confidence in itself
If the government felt it had no other way of forcing an early election, it could in theory call a motion of no confidence in itself.
In order for it to succeed, Conservative MPs would have to vote to bring down their own government.
While such a tactic might appear extreme to outside observers, it would trigger an automatic early election - as long as opposition parties failed to form an alternative government within the 14 days.
As such, this option would be extremely high risk.
Brexit - British exit - refers to the UK leaving the EU. A public vote was held in June 2016, to decide whether the UK should leave or remain.
- A simple guide to Brexit
- Could a no-deal Brexit still happen?
- What is in Boris Johnson's Brexit plan?
- What will happen to the EHIC after Brexit?