After the worst electoral defeat since 1935, Jeremy Corbyn said he would not lead the party into the next election, but is staying in place until his successor is named on 4 April.
Here are some are the candidates who have announced they are running in the leadership race.
Lisa Nandy: The 40-year-old MP for Wigan became the fourth Labour figure to declare she is standing for the leadership, in a letter to the Wigan Post. One of a clutch of shadow ministers who resigned from Jeremy Corbyn’s frontbench after the Brexit referendum, she has been urging her party to concentrate on winning support in smaller towns.
Sir Keir Stramer: The 57-year-old shadow Brexit secretary used an article in the Sunday Mirror to announce he is running to replace Mr Corbyn. Likely to be seen as the centrist candidate in the race, Sir Keir said Labour needs to “rebuild fast” to restore trust. A passionate Remainer, he was director of public prosecutions before entering Parliament.
Rebecca Lond-Bailey: The 40-year-old shadow business secretary is another MP to announce she is considering going for the top job. One of a new generation of MPs on the left of the party who is close to Mr Corbyn’s inner circle, she represented Labour in a TV debate during the election.
Jess Phillips: The 38-year-old Birmingham Yardley MP became the third Labour figure to declare she is standing for the leadership. She has been one of the most outspoken critics of Jeremy Corbyn’s leadership and the party’s record on tackling anti-Semitism, bullying and harassment.
Emily Thornberry: The 59-year-old shadow foreign secretary was the first to declare she is running to succeed Mr Corbyn. She deputised for him at Prime Minister’s Questions but was replaced after publicly calling for Labour to back another EU referendum.
Yvette Cooper: The 50-year-old, a former cabinet minister under Gordon Brown’s premiership, said last month that she would “decide over Christmas” whether to stand, and has made no statement since then. She was an unsuccessful challenger to Jeremy Corbyn during the 2015 leadership contest.
Clive Lewis: The 48-year-old shadow Treasury minister resigned from the party’s frontbench last year in order to oppose the bill triggering the Brexit process. An early supporter of Jeremy Corbyn, he rejoined in January last year.
A new deputy leader also has to be elected after Tom Watson stepped down in December and Labour’s National Executive Committee (NEC) will also set the rules for that contest.