Jeremy Corbyn announced he was stepping down in December following a humiliating defeat to the Conservative Party, and now three Labour candidates are jostling for position in the race to become the leader of the opposition.
Tonight on Channel 4 the contenders will pitch their polices to Labour members across the country and question rivals in a head-to-head special.
Here's everything you need to know about the debate.
Where and when is the debate taking place?
The debate takes place at 8pm tonight (February 17) on Channel 4. Voting begins just a few days after the debate on February 21, with the result announced on April 4.
Viewers who miss the debate can catch up on the channel's streaming platform, All 4.
Who is hosting the debate?
Veteran Channel 4 news presenter Krishnan Guru-Murthy will referee the debate. The 49-year-old presented the broadcaster's Alternative Election Night coverage in December
Who's taking part in the debate?
Emily Thornberry was eliminated from the race on Saturday after she failed to earn the required number of nominations, reducing the contest o a three-horse-race.
Shadow business secretary Rebecca Long-Bailey, Wigan MP Lisa Nandy and Shadow Brexit Secretary Keir Starmer will all be put under scrutiny by Guru-Murthy.
What format will the debate follow?
The three candidates will be asked questions by the audience with Guru-Murthy in charge of setting topics and ensuring that each member is offered an equal opportunity to present their answers.
Who's dropped out of the race so far?
Since Jeremy Corbyn announced that he was stepping down the leadership role has shrunk from six to three.
Clive Lewis and Jess Phillips both failed to gain traction in their campaigns both departing in January.
Emily Thornberry was eliminated form the debate on February 15 following her failure to earn the require amount of nominations.