The UK has been split since 51.9 percent of people in 2016 voted for the country to leave the European Union, but the political crisis has now reached a new crunch point. Here's a guide.
Boris Johnson became leader of the governing Conservative Party in July with a pledge that whatever happened, the UK would be leaving the European Union on October 31 – with or without a deal with the EU. Although MPs have yet to show there is a majority for any specific type of Brexit, there is a majority against the idea of what is called a no-deal Brexit.
If nothing else changed in Parliament and Johnson and the EU did not reach an agreement, the default position at the moment is that the UK would leave the EU without a deal – covering things such as trade, travel and finances.
So, MPs took the unusual step on Tuesday of taking control of Parliament's agenda away from the government by calling and winning an emergency vote. They did this so they can now try to put into law a rule that, if the EU agrees, Brexit day would be postponed to 31 January 2020, unless Boris Johnson agrees a deal with the EU before 19 October and MPs back it.
If this law passes through Parliament, it effectively rules out the chance of a no-deal Brexit.
The result of the vote in the House of Commons on Tuesday evening was 328 backing the attempt to block a no-deal Brexit, with 301 opposing the plan. As expected, the Conservative Party and its Democratic Unionist Party allies mostly opposed the bill – but the reason the vote was lost was because 21 Conservative MPs rebelled against their party line and voted to block no-deal.
These rebels included some of the best known and experienced Conservatives – such as the UK's longest-serving MP, Ken Clarke, who was chancellor in the 1990s, Philip Hammond, who was chancellor until July this year and the long-serving Sir Nicholas Soames, who is Sir Winston Churchill's grandson.
They were warned ahead of the vote that they would be expelled from the parliamentary party if they rebelled, and told they would not be allowed to stand as a Conservative candidate at the next election.
So, what happens now?
Prime Minister Boris Johnson stood up in the House of Commons after the result was announced and said MPs were on the "brink of wrecking" the chance of being able to strike a deal with Brussels if they took away the threat of the UK leaving the EU without a deal. It would, he said, mean "more dither, more delay and more confusion."
He said that, because of this, he was going to call for a swift general election so the public "can choose" who represents the UK at the EU summit on October 17 and decide whether Brexit happens on October 31 and, if so, what form of Brexit it is.
But… for there to be an election, Johnson needs two-thirds of MPs to vote for an election. And the leader of the biggest opposition party – Labour's Jeremy Corbyn – has said his party will not vote for a general election to be held until the bill ruling out the possibility of a no-deal Brexit has become law.
Corbyn said: "We live in a parliamentary democracy, we do not have a presidency. Prime ministers govern with the consent of the House of Commons representing the people in whom sovereignty rests. There is no consent in this House to leave the EU without a deal."
Because of the way the UK parliament works, the bill ruling out a no-deal Brexit is not likely to become law until next Monday at the earliest, so it seems unlikely Johnson, whose party has less than 50 percent of MPs, will be able to get the required 66 percent of MPs to prompt a general election when they vote on the plan.
An alternative option would be for a vote of no confidence in the government – if Johnson loses, there would then be 14 days for another MP to show they can command a majority in the House of Commons. But if no-one can demonstrate they have a majority, there would be a general election, with Johnson going into it as prime minister. Theoretically, that election could be held after October 31, meaning a no-deal Brexit could still happen.
And, of course, if an election were held before October 31, Brexit is likely to be the key issue, with any change in the make-up of MPs in the House of Commons likely to have a big impact on what happens next.
But at the moment, the options of the UK leaving the EU without a deal, a fresh delay to Brexit, and a referendum with the option of canceling Brexit altogether remain. The next few days' votes will be crucial in deciding which of these options is likely to happen.