The next leader of the Labour Party is set to be announced on Saturday.
Who is standing in the contest?
There are five contenders. Former Foreign Secretary David Miliband, his brother and former Energy Secretary Ed Miliband, former Schools Secretary Ed Balls, former Health Secretary Andy Burnham and backbencher Diane Abbott, the UK's first female black MP.
Read more about the hopefuls.
How did they become candidates?
Candidates could not simply declare they wanted to stand. Each had to be nominated by 33 Labour MPs in order to get onto the ballot paper. Three candidates - David Miliband, Ed Miliband and Ed Balls - secured sufficient nominations well before the deadline last month but Andy Burnham and Diane Abbott only passed the threshold on the day itself. Another intended candidate, MP John McDonnell, pulled out of the race and encouraged his backers to transfer their support to Diane Abbott to make sure she qualified.
How long will the contest take?
Voting took place between mid-August and mid-September with the winner being announced on 25 September ahead of the first day of the party's conference in Manchester. Party officials believed the contest, triggered in May, should not be rushed saying Labour should have as full a debate as possible on the party's future direction. The candidates set out their stalls in a series of hustings up and down the country.
Who can vote in the contest?
Labour MPs, Members of the European Parliament (MEPs), party members and members of affiliated organisations, such as trades unions and socialist societies, are all entitled to vote in the election. Nearly a million people voted in the last contested election, in 1994. Anyone who joined the Labour Party by 8 September was eligible to vote.
How is the vote conducted?
The vote is broken down into three sections, known as an electoral college. Labour MPs and MEPs, party members and members of affiliate organisations are all balloted individually and the results from the separate categories each make up a third of the final result. In 1994, Tony Blair won the backing of 60% of MPs/MEPs, 58% of party members and 52% of affiliate organisations. His nearest challenger, John Prescott, got 19%, 24% and 28.4% of the votes respectively. The share of the vote from each category is divided proportionately to get the final result. Mr Blair won the contest with a 57% share of the overall vote. In Labour's 2007 deputy leadership election, it was decided that no-one could win outright with less than 50% of the vote. The candidates with the fewest votes were successively eliminated and their second preferences distributed to other candidates until Harriet Harman won in the fifth round. The Labour Party's ruling National Executive Committee (NEC), in charge of the election rules, will decide what process to follow this time.
Who is in charge in the meantime?
Deputy Labour leader Harriet Harman has been acting leader until the election takes place.
When is the result being announced?
The result of the vote is expected at about 1630 BST on Saturday, in Manchester, ahead of the start of Labour's annual party conference.