The Staggers 4 July 2016 How does the Labour leadership contest work? Here’s what will happen if Jeremy Corbyn is challenged. Getty Sign UpGet the New Statesman\'s Morning Call email. Sign-up With mass resignations from the Shadow Cabinet - and increasing pressure on Jeremy Corbyn to resign - it’s looking more and more likely that a Labour leadership contest is on the cards. Why is a challenge likely? Corbyn has come under fire since the result of the EU referendum. Labour MPs have criticized a lack of leadership and lackluster campaigning in the run-up to the vote. Last week, Corbyn lost a vote of no confidence amongst Labour MPs by 172 to 40. Although not constitutionally binding, it has proven beyond doubt his dwindling level of support within the parliamentary Labour party (PLP). The concurrent Tory leadership race – and the possibility of a general election when the new Prime Minister is installed – is further fuelling antagonism. Many Labour MPs believe he would struggle to win if a snap election is called. Why hasn’t he resigned already? Corbyn still has a lot of grassroots support, as demonstrations across the country have shown. Momentum, as well as John McDonnell, have called attempts to depose Corbyn a “subversion of democracy”, citing his overwhelming mandate in the leadership election last September as evidence. Earlier today, Corbyn posted this video to his Twitter account: After the events of the past week, I wanted to talk directly to Labour Party members.https://t.co/mmLLLCIsL5 — Jeremy Corbyn MP (@jeremycorbyn) 4 July 2016 What needs to happen in order for a challenge to take place? Any person wishing to challenge the leader needs to secure the support of 20 per cent of Labour MPs and MEPs. Labour currently have 251 MPs and MEPs – so 51 would need to back the challenger. Once this is assured, the candidate would need to formally write to the General Secretary of the Labour Party, thereby enacting a leadership contest. And if Corbyn resigns? If the leadership is vacant, each candidate requires only 15 per cent of MPs and MEPs to support them, rather than 20 per cent - that’s 38 . Who will run? As of yet, no-one has officially launched a challenge. Angela Eagle has said she will mount one if Corbyn doesn’t quit. Yesterday, she claimed she had enough “support to run and resolve this impasse”, and warned “I will do so if Jeremy doesn’t pay attention soon.” Opponents of Corbyn will want to resolve around one candidate. But it remains to be seen whether MPs agree that Angela Eagle is the best to oppose the current leader. Other potential runners include Owen Smith, Yvette Cooper and Dan Jarvis. Can Corbyn stand again? Corbyn is likely to insist he appears on the ballot paper in any leadership contest. But the constitutional legitimacy of this is still ambiguous. Some have suggested he would need the support of at least 50 MPs for that to happen. The result of the no confidence motion implies this is unlikely. How would a vote work? Using a system called One Member One Vote (OMOV). This means candidates will be elected by members and registered and affiliated supporters – each has a maximum of one vote. It didn’t used to be like that, did it? No, it used to be a different system, with three electoral colleges (party members, MPs and MEPs, and trade unions and affiliated societies) being given equal weight. So now, if you’re a Labour-affiliated trade union member and you want to vote, you have to register as a Labour supporter (rather than automatically being affiliated). When did it change? It was part of the Collins Report’s proposals for party reform in 2014. Last year’s leadership contest was the first time it was used. What’s the voting system? Alternative Vote (AV), as in previous leadership elections. How long will it all take? If an election contest is triggered, it’s likely the winner will be announced at the party conference in late September. What will happen? Regardless of his standing within the PLP, if Corbyn is able to stand, it will be a close contest because of his high level of grassroots support. › As Jeremy Corbyn calls the Labour rebels' bluff, what's their next move? Subscribe For more great writing from our award-winning journalists subscribe for just £1 per month!