John Bercow announced he will resign as Speaker of the House of Commons at the end of October, after holding the position for a decade.
The Speaker chairs debates in the Commons Chamber and is elected by MPs. They must remain impartial at all times.
MPs from across parties have already confirmed their interest in the position.
Here’s who has thrown their hat in the ring so far.
Labour MP Rosie Winterton has been deputy Speaker since 2017.
The Doncaster Central MP has said she would be a "stabilising, unifying Speaker" if chosen, and would "help resolve the tensions" in Parliament.
Sir Lindsay Hoyle
Labour’s Sir Lindsay is the MP for Chorley and also currently holds the post of deputy Speaker.
He announced that he was putting himself forward on Twitter, writing: “Now that there is a vacancy for the Office of Speaker of the House of Commons, I am happy to confirm that I will be standing as a candidate.”
Former Labour minister Harriet Harman said if she became the next Speaker, she would be she would be “a champion for Parliament”.
The MP for Camberwell and Peckham has also served as leader of the House of Commons.
She said: "I think the Speaker has to be scrupulously neutral as between different views within the House."
Dame Eleanor Laing
Eleanor Laing (centre) has confirmed her interest in the role
Conservative Eleanor Laing has been the MP for Epping Forest since 1997 and was has been deputy Speaker since 2013.
She called Mr Bercow's resignation an "historic moment", writing on Twitter: "He has been a friend of mine for 32 years and has achieved an enormous amount during his tenure. I wish him well.
"There will be a vigorous campaign to succeed him and I am happy to confirm I will be a candidate."
Labour's Chris Bryant said he was running for the position because he wants "to do things properly" and called for Parliament to "change with the times".
The Rhondda MP said in an email to MPs that as Speaker he hopes to be a "breath of fresh air".
His ideas include ensuring Prime Minister's Questions sticks to a 30-minute window, as well as calling colleagues "according to their relevance rather than their seniority" during debates.
Sir Henry Bellingham
Sir Henry Bellingham has confirmed his candidacy and said the Commons "needs a change in style and tone".
The Conservative MP for North West Yorkshire told talkRADIO that if he was elected, he would look to bring back old ceremonies and traditions, including wearing a wig and gown to symbolise the importance of the office over the individual.
He called the outgoing Mr Bercow an "outstanding Speaker in many ways" and a "champion of the backbencher".
The MP for Hackney South and Shoreditch said it was time for another female speaker.
Meg Hillier wrote on social media: “I am standing for Speaker in the House of Commons. Lots to build on to make Parliament work better for Members, staff, and the people who vote for us.
"There’s only been one woman in over 600 years – time for another. #honest #straightforward #fair.”
Ms Hillier told talkRADIO that her priorities in the role would be to “uphold the rules and the constitution, and to curtail the power of any future Government which gets too big for its boots”.
She also promised to make PMQs an hour long, once a week, to let all backbenchers quiz the Prime Minister.
Sir Edward Leigh
Sir Edward Leigh is the Conservative MP for Gainsborough.
He was one of the first to announce his candidacy with a simple tweet: "I confirm that I will stand for the office of Speaker."
Shailesh Vara spent a dozen years on the Conservative frontbench, which included a stint as second-in-command in the Northern Ireland office.
He said: “I believe I have the necessary experience to lead the way having served in a variety of roles including as a Minister, a government whip, a shadow minister and a backbencher.”