Tuesday’s crunch meeting of Labour’s ruling national executive committee (NEC) to agree the manifesto for the European parliament elections will be the latest round of an argument that has been raging at the party’s highest levels for months.

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Here is where some of the key players stand:

Union leaders

The GMB’s general secretary, Tim Roache, uses the analogy of a workplace agreement struck between unions and management to explain why he thinks any deal made between Labour and the Tories must be subject to a public vote. Once union reps have struck an agreement behind closed doors, they would then put it to members.

He is perhaps the clearest advocate of a public vote. Unison’s Dave Prentis told Jeremy Corbyn at a recent meeting that if Labour achieves every one of its Brexit demands in full a referendum might be unnecessary – but he thinks that is highly unlikely. Unite’s general secretary, Len McCluskey, meanwhile, remains a referendum-sceptic, fearing voters would see a referendum as a betrayal.

Tom Watson

Labour’s deputy leader is the most outspoken advocate of a referendum in public, attending the recent Put it to the People march, and even calling for party supporters to lobby their NEC reps to demand the manifesto includes a confirmatory referendum. His position is broadly supported by a group of other shadow cabinet members, including Emily Thornberry.

Keir Starmer

The shadow Brexit secretary has been relatively cautious in his public statements – but regards himself as the guardian of Labour’s conference motion on Brexit, of which he oversaw the drafting.

The motion ends with the phrase: “If the government is confident in negotiating a deal that working people, our economy and communities will benefit from they should not be afraid to put that deal to the public” – which Labour remainers regard as a pledge of a referendum on any deal.

Backbench supporters of a “people’s vote” regard Starmer as their champion inside the cross-party Brexit talks, hoping he will insist on a confirmatory vote.

John McDonnell

McDonnell is a Eurosceptic, who has warned that a referendum could stoke the arguments of far right campaigners. But he is also a staunch defender of the Corbyn project, which relies on enthusiastic activists, many of whom are keen to see Brexit reversed. For that reason, he has offered conditional support to the idea.

Other converts to the idea of a referendum include Diane Abbott, who is a strong remainer in a heavily remain constituency, but has concerns about how another campaign would play out.

Rebecca Long-Bailey

As shadow business secretary, Long-Bailey has been attending the cross-party talks with the government, and has begun to make herself the public face of party scepticism about a referendum, making clear on Sunday that if Labour gets what it has asked for from the negotiations, the outcome should not have to be put to the public.

She was part of a delegation, including Jon Trickett, Richard Burgon, Andrew Gwynne, Ian Lavery and others, that went to see Corbyn during the indicative votes process earlier this month to object to Labour’s backing for the motion on a confirmatory referendum.

Like Trickett and others, Long-Bailey fears the impact on voters in leave constituencies of Labour appearing to be a remain party.

Love Socialism Hate Brexit

Corbyn-supporting MPs – including the frontbencher Clive Lewis – have formed an increasingly vocal campaign group, urging the Labour leader to back a referendum.

Lewis resigned from a shadow ministerial job in 2017 rather than follow the whip and vote for triggering article 50; and has made a series of spiky interventions in recent months, including warning that if Brexit goes ahead, “your children, or possibly our grandchildren, but probably our children, could be back in Europe in a few years time – but in uniform”.

Other members of Love Socialism Hate Brexit, which cooperates with members of other parties through the umbrella group Another Europe is Possible, include Lloyd Russell-Moyle and Rachael Maskell.

Momentum

Set up by the veteran leftwinger Jon Lansman to campaign for Corbyn’s leadership, Momentum has repeatedly hedged its bets on Brexit, an issue that has divided the Labour leader’s leftwing backers.

National organiser Laura Parker is an ardent supporter of a referendum but Lansman has been more cautious – though he has more recently edged closer to supporting a referendum to break the deadlock in Westminster, and was expected to support that position on the NEC.