Jeremy Corbyn is to propose a democratic revolution in the Labour party that would give its mass membership a role in both electing his top team and shaping party policy. With a comprehensive victory in the leadership contest next weekend looking increasingly likely, the Labour leader is now planning the next phase of a radical remaking of the party into a democratic social movement.

It is understood that Corbyn will suggest that members should be allowed to elect some shadow cabinet ministers, and have a direct say in policymaking through “digital consultations”.

In what will be presented as a conciliatory move to unify the party, one proposal is that a third of shadow cabinet posts are elected by the parliamentary party, another third by the leader and a final third by members. A source said: “These things are open to discussion”.

The winner of the leadership contest will be announced on Saturday at a special conference in Liverpool. A source close to Corbyn said: “I would be disappointed if we did not beat last year’s figure and get closer to 65% or even better.”

The idea of involving the membership in shadow cabinet elections is a rebuff to the deputy leader, Tom Watson, who is due to present a motion to Labour’s governing body, the NEC, on Tuesday in favour of bringing back the system under which MPs alone have a vote.

However, it is understood Watson recognises that the changes being suggested by the leader could represent “an exciting new era in British politics” under which for the first time frontbenchers would be delegates and not representatives of the membership. The changes, Watson believes, would ensure that Labour will look more like Syriza in Greece than the traditional party of the unions and deliver “a new era of digital democracy”, according to one source. “If proposed by Jeremy on Tuesday, he will consider them deeply,” the source said.

It is understood that some MPs also believe there is a case for the membership to be the sole electorate of the front-bench to ensure shadow cabinet ministers have an equal standing.

Deputy leader Tom Watson says Labour will look more like Syriza than the traditional party of unions. Photograph: David Levene/The Guardian

Corbyn said he wanted to “push forward democracy in our party at every level”. “Whoever wins the leadership election has the right to call on support from the Labour party at all levels, including in parliament,” he said. “If Labour party members re-elect me, that will be my second mandate in a year, from a hugely increased membership. It’s right that we’ll be discussing elections to the shadow cabinet at the national executive committee this week, as well as who might take part in those elections, and how to ensure proper representation of the regions, nations, gender and ethnicity. Democratisation of the party and the country is central to my agenda for change.”

A source close to the Labour leader said that they were not presenting the changes on a take-it-or-leave-it basis, but hoped to spur a discussion at the NEC early this week – a date dubbed by one campaigner as “Super Tuesday”.

A second source said: “The whole question is how to make the party more participatory. It is part of a wider agenda of democratising the party. Before the vote on whether to bomb Syria in November last year the party held a digital consultation of members. That is the kind of approach we can build on.”

At last Tuesday’s meeting of the shadow cabinet, several members, including the chief whip, Rosie Winterton, spoke in support of returning to a system, abolished by Ed Miliband, under which the parliamentary party elects most members of the shadow cabinet, with the rest being appointed by the leader. Winterton said she believed such a change would help restore unity between the leader and his MPs and would encourage many who had resigned in June to return to the fold.

However, a move instead to give the mass membership a role both in shadow cabinet elections and over policy will be seen by many elected members not as a peace offering but as a sign of Corbyn’s determination to marginalise his MPs and put power in the hands of ordinary members. While the question of whether to rejoin the frontbench should Corbyn win is a live one in the party – described by some as a choice of whether to “sulk or serve” – a move to give the membership a vote in shadow cabinet elections was dismissed as “unacceptable” by one of the shadow cabinet ministers who resigned in June, who added: “Two-thirds of the shadow cabinet would be his people – this isn’t a way to bring the party back together.”

A second serving shadow cabinet minister rejected the plan to allow the membership a say as a “recipe for chaos” for which there was no appetite outside the leader’s office.

A member of the NEC said that the plans would provoke a massive row on Tuesday: “It is about Jeremy’s determination to boost his power base.”