Last night Theresa May suffered the biggest defeat for a government in 100 years after MPs voted resoundingly against her Brexit deal.
Jeremy Corbyn has tabled a motion of no confidence in the government for this evening.
So is the UK on course for an early general election?
What is happening tonight?
Labour have been agitating for a vote of no confidence in the government for weeks now. Last night, they pulled the trigger and tabled the motion.
Remember, this is not the same as the confidence vote Mrs May faced in December, which was about her status as leader of the Conservatives. Tonight’s ballot is about the government’s control of Parliament.
It used to be in the gift of the Prime Minister of the day to decide when a general election is called. But since 2010, the Fixed Term Parliaments Act has made things more complicated. That legislation – designed to prop up Conservative Lib Dem coalition – sets out a few constitutional hurdles that must be cleared before we get to a general election.
First of all, a majority of MPs must vote for the motion “this House has no confidence in Her Majesty’s Government” which is what Labour hope will happen tonight.
What are Labour’s chances of defeating the government this evening?
You might think after last night’s crushing defeat, Mrs May is certain to lose this evening’s vote.
But unlike yesterday, which was all about the deal, the Democratic Unionists have said they will back the Conservative government in a confidence vote.
In many ways, that makes sense: why would the DUP would risk triggering an election when they hold the balance of power in the Commons? Their “confidence and supply” arrangement with the Conservatives has already benefited Northern Ireland to the tune of £1 billion. And the party has suggested in the past that the Tories will always have its backing as long as Mr Corbyn is Labour leader because of his stance on Northern Ireland.
So how many votes are needed to pass the confidence motion?
There are 650 MPs in the Commons, of whom four don’t vote because they are the Speaker and Deputy Speakers (two Conservatives, two Labour members). Then we’ve got the seven Sinn Féin MPs who don’t take their seats in Parliament, plus the two Tory and Labour MPs on each side who will be “tellers” for the vote, and we’re left with 635 potential voters in tonight’s ballot.
Assuming all of those members vote (some may not due to illness, for example), that makes the magic threshold 318.
If all DUP and Conservative MPs back Mrs May tonight, that will leave her with 323 votes in her favour. If Mr Corbyn manages to get every Labour, SNP, Liberal Democrat, Independent, Plaid Cymru and Green MP on board, he will have 311 MPs voting with him against the government. As it stands, that’s not enough to defeat Mrs May.
So Mr Corbyn would need at least a handful of Conservative MPs to rebel against their party and join him in order to get over the first hurdle to a general election.
What if the government does lose tonight?
Back to the Fixed Term Parliaments Act. If the government is defeated in a confidence vote, we’re in 14 days of frantic limbo as the Conservatives, and potentially other parties, try to gain or regain control of Parliament. If no-one can secure the support of a majority of MPs in that time, an election is called.
So if Mrs May loses tonight’s vote, she has a second chance to stay in power.
Again, Mr Corbyn would be working with the same parliamentary arithmetic, so he’d almost certainly need a cross-party coalition, including a chunk of Conservative MPs, to block Mrs May from regaining control of the Commons.
Two things must happen before the UK will return to the ballot box for a general election.
The government must lose a confidence vote in the Commons, like the one tabled for this evening. Then there’s 14 days during which the Conservatives, and potentially other parties, can try to form or re-form a government. If no-one can manage that before the clock runs out, Britain will be back at the polls.
Labour will need at least 320 MPs to join them if they want to defeat the government in the confidence vote. That would require every Labour, SNP, Lib Dem, Independent, Plaid Cymru and Green MP – plus a handful of Conservative/DUP members – to back Labour.
If the government is defeated, Mrs May has a second chance to stay in power: that 14-day limbo. Mr Corbyn would be faced with the same parliamentary arithmetic, and would again need a chunk of Conservative MPs on his side to block Mrs May’s attempt to re-form her government.