Labour’s ruling body will decide on Tuesday whether the party will campaign for a public vote on any Brexit deal, Jeremy Corbyn has said on the campaign trail in leave-voting Peterborough.

Almost 90 Labour MPs and MEPs, including a number of frontbenchers, wrote to the party’s National Executive Committee (NEC) to demand that its European election manifesto include a “clear commitment to a confirmatory public vote on any Brexit deal”.

However, Corbyn declined to guarantee the commitment. He stressed that he was not a dictator and that the matter would be for the NEC to decide.

“The national executive will decide on Tuesday what will be in the European election manifesto, and we will reflect the decisions made [at] last year’s Labour party conference, which were for a customs union, market access and rights protection within – with – the European Union,” he said.

“We would prefer to have a general election, but failing that, if we get that agreement, we are prepared to consider putting it to a confirmatory vote. That is a decision the national executive of the party will make.

“It’s important that the party, which is a democratic party structure, makes those decisions. Sadly – or perhaps it’s a good thing – I’m not a dictator of the Labour party.”

Corbyn’s visit to the east of England comes amid an internal row over the wording of a draft Labour election leaflet. A number of pro-EU Labour MPs were angered by the absence of a reference to another referendum.

On Saturday afternoon, the BBC reported that the leaflets would be reprinted to refer to Labour’s preparations for a general election, with a referendum if necessary to avoid what it calls a “bad Tory deal”.

However, suggestions of a U-turn were downplayed by Corbyn’s office. “There are a number of different texts for different leaflets in circulation, including for a freepost and for other campaign purposes,” a spokesperson said. “They all reflect existing party policy. Our manifesto for the European elections will be decided in due course.

Shadow Treasury ministers Clive Lewis and Anneliese Dodds, shadow minister for the disabled Marsha de Cordova and shadow minister for industrial strategy Chi Onwurah are among the frontbenchers backing the call for a referendum.

Our letter to the @UKLabour NEC.



Our European elections manifesto must have a clear commitment to a confirmatory public vote on any Brexit deal. pic.twitter.com/MLUPOOERWZ — Love Socialism Hate Brexit (@LoveSocialism) April 26, 2019

Backbencher David Lammy told the Guardian that he hopes Corbyn will use the European elections to restore hope around the country and make an unambiguous commitment to a second referendum.

“I hope Jeremy Corbyn will use the European elections to tell the country the truth: the problem is not Theresa May’s withdrawal agreement, the problem is Brexit itself,” he said. “After years of broken promises, disastrous negotiations and global humiliation, our party has an opportunity to restore hope in the country with a vision of the UK that cooperates and leads internationally from within the EU.

“If Labour does not unambiguously choose to make a firm commitment to offering a referendum with the option to remain on any Brexit deal, I worry we will lose millions of pro-EU supporters for a generation.”

After lengthy discussions at the party’s conference in 2018, Labour committed to keep “all options on the table, including campaigning for a public vote” if there was not a general election.

In an interview with BBC Radio 4’s Today programme on Saturday, Richard Corbett, the leader of Labour’s MEPs and a member of the NEC, said he expected the party’s governing body to back a confirmatory public vote on any Brexit deal presented by the government.

“We have got to the point now where not holding another referendum is tantamount to saying to the general public, ‘You had your say three years ago, now you have to shut up and let the politicians serve up whatever they want to and you can’t have a say on it,’” he said.

The letter from 75 MPs and 14 MEPs organised by the Love Socialism, Hate Brexit group sets out plans to beat Nigel Farage’s Brexit party with “a message of hope and solidarity” before Tuesday’s meeting.

“Labour has already, rightly, backed a confirmatory public vote,” the letter states. “The overwhelming majority of our members and voters support this, and it is the democratically established policy of the party.

“We need a message of hope and solidarity, and we need to campaign for it without caveats.”