Keir Starmer is set to reignite a Labour party row over how it selects its leadership, seeking to rewrite the rules that led to the rise of Jeremy Corbyn. Here’s the lowdown on the changes. What is Starmer proposing? Starmer briefed his shadow cabinet that he would propose three new things at Labour conference: a return to an electoral college for leadership elections; a new reselection process for MPs; and a new policymaking process that does not involve “an endless series of motions at party conference”. How does Labour currently select its leader? Labour members and supporters pick the leader based on a one-member, one-vote system. It means that all members, whether they are in the shadow cabinet or registered supporters or affiliated trade union members, have a vote of equal value. But not all candidates make it to the members’ ballot. Under changes brought in under Jeremy Corbyn, any MP who wishes to stand must receive nominations from not only 10% of MPs – a reduction from the previous rules – but also from local parties, unions and affiliates too. How would the new system work? Starmer is proposing a change back to the old electoral college system – the same one that elected Ed Miliband. It was Miliband who then changed the system in 2014 to one member, one vote. The change back would mean that leaders are elected with a third of the vote coming from MPs, a third coming from trade unions and a third coming from members. It would give significantly more power to MPs to choose a future leader, but Starmer also plans to extend the vote to millions more trade union members. Why is Starmer doing this now? Starmer’s team say he wants to strengthen the trade union link and give their members more power. They say the changes would also end many protracted internal debates about how the party makes policy and selects MPs. “We need party reforms that better connect us with working people and reorient us toward the voters who can take us to power,” Starmer told his shadow cabinet. However, Starmer’s allies on the NEC say this is also about showing a definite break with the Corbyn era. Starmer’s hand is strengthened because internal analysis seen by the Guardian shows that the majority of Labour delegates – party members chosen by their local parties to attend and vote at conference – are pro-Starmer. That means Starmer has a chance – perhaps his only chance – to make some definitive reforms. Why would trade unions back it? Some leftwing unions, Unite, CWU and TSSA, have already said they will not back it and will push for any decision to be delayed. The power now lies with the GMB, Unison and Usdaw, whom Starmer must convince. The big draw is that union members can currently vote in leadership elections only if they have actively signed up as affiliate Labour supporters. Starmer’s proposal would extend the vote to all trade union members who pay the political levy on their union fees, potentially expanding the leadership electorate to more than 2 million people. Why does the Labour left oppose the change? The electoral college system gives members far less power to decide who is Labour leader. It means that Labour’s 400,000 members would have the same weight as Labour’s 199 MPs. Momentum has called it “a new low in Starmer’s leadership” and said his pledges of unity and leftwing policy made during the leadership campaign were “barefaced lies”. What happens if the vote goes to conference? Starmer’s allies believe they can win the vote. But if one big union such as the GMB or Unison decides to vote against the changes, it will be incredibly tight and Starmer could lose. If he does lose, his team say it will show nonetheless that he is willing to take risks, but it will be a humiliating start to a crucial conference.