What could happen next in Labour leadership challenge?

How a contest to become PM is triggered, and Andy Burnham’s chances in the Makerfield byelection

• UK politics live – latest updates

A contender is declared the winner if they get more than 50% of first preferences. The winner then becomes the new leader of the Labour party.

Failing that, the candidate who places last is eliminated, and the voters who put them as their first choice will have their votes moved to their second-choice candidate.