MPs will elect John Bercow’s successor as Speaker of the House of Commons later in the first election for the powerful post in more than a decade.
The Speaker keeps order in Commons debates and calls MPs to speak.
Seven candidates are in the running, including ex-deputy Labour leader Harriet Harman and current deputy Speaker Sir Lindsay Hoyle.
At 14:30 GMT the candidates will make short speeches in the Commons after which MPs will cast their votes.
Mr Bercow stood down on Thursday after an eventful and frequently controversial decade in the Speaker’s chair. His resignation as MP for Buckingham was officially confirmed on Monday.
How will the vote unfold?
Candidates need the support of at least 12 MPs, three of whom have to be from a different party, in order to be eligible to take part.
After the candidates have made their pitches in the Commons, MPs will have 20 minutes to vote in a secret ballot. It will take about an hour to count them.
If no candidate receives more half of the votes, the individual who receives the least votes will drop out, as will anyone who obtains less than 5% of the total cast.
After each round, there will be a 10-minute period for candidates to withdraw.
MPs will then continue to vote until one candidate obtains more than half of the votes. The process will be overseen by Ken Clarke, who as Father of the House is the long-serving MP in the Commons.
Who is in the running?
The seven contenders are:
- Chris Bryant – former minister and shadow Commons leader; Labour MP for Rhondda since 2001
- Harriet Harman – former minister and deputy Labour leader; Labour MP since 1982, for Peckham and its successor constituency Camberwell
- Meg Hillier – chairwoman of the Public Accounts Committee and former minister; Labour MP for Hackney South and Shoreditch since 2005
- Sir Lindsay Hoyle – elected Labour MP for Chorley in 1997; elected deputy Speaker in 2010
- Dame Eleanor Laing – elected Conservative MP for Epping Forest in 1997; elected deputy Speaker in 2013
- Sir Edward Leigh – Conservative MP for Gainsborough since 1983; former chairman of the Public Accounts Committee
- Dame Rosie Winterton – elected Labour MP for Doncaster Central in 1997; former Labour chief whip; elected deputy Speaker in 2017
BBC parliamentary correspondent Mark D’Arcy said most observers believed Sir Lindsay – who has been Mr Bercow’s senior deputy for years – was the frontrunner.
“As Chairman of Ways and Means, he chairs Budget debates and selects amendments for committee stage proceedings on bills, and has had plenty of opportunity to demonstrate his credentials,” our correspondent says.
Sir Lindsay said MPs backing him included Conservative Charles Walker, who was one of Mr Bercow’s key allies during his tenure, former sports minister Tracey Crouch and Brexit-backing Labour MP Caroline Flint.
He received an early boost when former Conservative minister Shailesh Vara, one of the outsiders in the contest, said he was pulling out and would be voting for his Labour colleague.
What is the Speaker’s role?
The role of the Speaker has come under increasing scrutiny over the past few years – and Mr Bercow has been both praised for boosting the influence of backbench MPs and criticised for stretching parliamentary rules.
Some have also accused him of not being impartial when it comes to Brexit.
The Speaker is responsible for choosing which amendments can be voted on – a power that has proved particularly significant in the Brexit process.
He is also in charge of upholding parliamentary rules, and Mr Bercow twice angered some MPs by refusing to allow the government to hold another vote on an already rejected Brexit deal.
The Speaker can also permit MPs to ask urgent questions whereby government ministers are summoned to the House of Commons over a time-sensitive or important matter.
During his years in the role, Mr Bercow dramatically increased the number of urgent questions asked.
Analysis: Easy win or tactical battle
By Mark D’Arcy, the BBC’s parliamentary correspondent
Later on Monday what one MP calls “the most duplicitous electorate in the world” will vote to choose a new Speaker of the House of Commons.
So what might MPs want? First, there seems be an appetite for a different style – an end to Bercow-esque grandiloquence and those five-minute appeals for brevity, as well as for an end to the kind of clashes with MPs that the departed Speaker was prone to.
Remember his red-faced finger-jabbing clash with the then Chief Whip Patrick McLoughlin, or this week’s spat with long-time Bercow critic Andrew Bridgen?
Then there’s the much more important concern about the Speaker’s sweeping powers to make the rules in the Commons, a power which saw him permitting amendments to Business of the House motions which were supposed to be taken “forthwith” – which many MPs believed meant they could not be amended.
Given no one party has a majority in the House, the winning candidate will be the one most capable of reaching across party lines, and building a majority out of factions of the main parties, the members of the smaller parties and their personal supporters.
Those seen as party gladiators first and foremost may find that hard to do.