Today, the first hustings takes place in Liverpool for the Labour leadership. But it’s also the first hustings for the deputy leadership, and while the role of a party leader is clear the role of deputy leader is ill-defined. There is no job description for deputy leader, and it’s barely referenced in the party rule book.

John Prescott is perhaps the definitive deputy leader of recent times, being elected deputy in 1994 and serving until 2007 – the longest in Labour party history. He is also one of the few from the New Labour era who still enjoys widespread affection across the party.

It was Prescott’s loyalty and ability to change the role to suit the needs of the party that defined his tenure

It was Prescott’s steadfast loyalty to his leader and ability to change the role to suit the needs of the party that defined his tenure. When New Labour was elected in 1997 he headed up a super-department in charge of implementing key New Labour policies. Later he became a campaigning presence, a link between the party and its members and an influential peacemaker within cabinet as the tensions between Blair and Brown increased.

Both the recent incumbents, Harriet Harman and Tom Watson (initially), combined the role of deputy leader with being party chair – an unofficial role appointed by the leader that has focused on campaigning and mobilising activists around the country. Roy Hattersley coupled the role with shadowing great offices of state, first shadow chancellor then shadow home secretary under Neil Kinnock, while before him Denis Healey was shadow foreign secretary under Michael Foot.

It will be up to each of the current candidates to shape the role in their image. From their statements, it appears that Ian Murray and Rosena Allin-Khan want to focus more on a party role, with the former focusing on listening to voters and members while changing the party’s processes and culture, and the latter pledging to work with the grassroots across the UK.

Richard Burgon, Dawn Butler and Angela Rayner could all be eyeing a bigger policy role, alongside a party role. Butler has emphasised her previous ministerial experience under Gordon Brown, and the U-turns she has forced on the Tories in opposition. Burgon has pledged to overhaul campaigning, messaging and selections, and to chair a special commission on rebuilding support in leave seats. Rayner, meanwhile, wants to challenge Tory cuts, privatisation, and environmental failure alongside a commitment to “community campaigning”.

In the wake of four election defeats, changing the party’s campaigning approach should be seen as a key priority, and the deputy could certainly take a lead on this while the leader concentrates on galvanising public support and selling Labour’s popular policies. Burgon, Butler and Rayner campaigned relentlessly round the country in 2019 so will have picked up key insights, and as the sole Labour MP in Scotland, where Labour urgently needs to regain ground if it is to win power, Murray might also stake a claim.

As Prescott demonstrated, loyalty is a discipline. He quipped about Blair in 1994, “he scares the life out of the Tories ... and me”. Once in office, he never publicly disagreed, even when his discomfort was palpable. The most recent deputy leader, Tom Watson, said in his 2015 acceptance speech, “I promise to back our new leader 100% … only through unity will come the strength we need to fight the Conservatives.” Very few members will think that promise endured.

Team relationships are important, but the deputy doesn’t have to be the key ally. The joint ticket of Rebecca Long-Bailey and Angela Rayner would clearly do that, but a deputy’s relationship with the leader doesn’t have to be so close. Blair had a closer relationship with Brown (initially at least) and Peter Mandelson than with Prescott, while Jeremy Corbyn was certainly closer to John McDonnell than to Tom Watson.

Many members will also consider what it says about the party if two men (for instance Keir Starmer and Burgon or Murray), or two Londoners (Starmer and Allin-Khan or Butler) win the races, though some would argue a joint ticket from Greater Manchester (Long-Bailey and Rayner) is too narrow as well.

Ultimately it is not the optics but the practicalities that matter. Labour needs the right duo who are capable of successfully promoting policies and reconnecting with parts of the country which turned blue. That means a focus on clear campaigns that mobilise members and resonate with the public. And that especially means a deputy who is a team player and focuses on uniting the party to campaign in the country not coveting the top job or factional organising.

According to a poll earlier this week, Rayner appears to be the firm favourite, but things can change fast in internal elections. Whoever Labour members elect as deputy leader in April 2020, it should be someone who is disciplined and loyal, with an ability to clearly define the role they will play. Like many thousands of Labour members and supporters, I will watch the debates with interest before making up my mind.

• Andrew Fisher was the Labour party’s executive director of policy from 2016 to 2019