Jeremy Corbyn has set out the four pillars of a “sensible” Brexit deal he would negotiate with the EU, as he pledged to carry out whatever the people decide in a second EU referendum as Labour prime minister.

The Labour leader set out how he would go into an election offering to negotiate a Brexit deal involving a customs union, ahead of next week’s party conference where activists will launch a bid to shift the party’s position towards campaigning to remain in the EU.

At the annual gathering in Brighton, some members will attempt to force a conference vote on the issue, with the aim of getting a promise to campaign for remain in the party’s next general election manifesto. Senior shadow cabinet figures – John McDonnell, Emily Thornberry, Tom Watson and Nick Brown – have all said they would want to campaign to stay in the bloc regardless of any Brexit deal negotiated by Labour.

However, Corbyn’s statement is the strongest sign yet that he will resist demands to pick a side and would opt to stay out of campaigning in a second referendum on a Labour-negotiated Brexit deal, allowing him to pitch himself as the neutral referee who pledges to carry out whatever the public decides.

This would help avoid the situation David Cameron found himself in as prime minister in 2016, when he resigned from No 10 after ending up on the losing side.

Writing in the Guardian, Corbyn laid down a marker of his determination to seek a better Brexit deal from the EU, which the party believes it could negotiate quickly based on conversations already undertaken with Brussels.

“A Labour government would secure a sensible deal based on the terms we have long advocated, including a new customs union with the EU; a close single market relationship; and guarantees of workers’ rights and environmental protections,” he said. “We would then put that to a public vote alongside remain. I pledge to carry out whatever the people decide, as a Labour prime minister.”

This would form the basis of what Corbyn describes as a “credible leave option” which would be offered at a referendum against the option of remaining in the EU.

Corbyn also positioned Labour as “the only UK-wide party ready to put our trust in the people of Britain to make the decision”, after the Liberal Democrats changed their position to campaigning for a revocation of article 50 in a bid to attract remain voters.

He said: “Johnson wants to crash out with no deal. That is something opposed by business, industry, the trade unions and most of the public – and even by the Vote Leave campaign’s co-convener, Michael Gove, who said earlier this year: ‘We didn’t vote to leave without a deal.’

“And now the Liberal Democrats want MPs to overturn the referendum result by revoking article 50 in a parliamentary stitch-up. It is simply undemocratic to override the decision of a majority of the voters without going back to the people.

“Labour is the only party determined to bring people together. Only a vote for Labour will deliver a public vote on Brexit. Only a Labour government will put the power back into the hands of the people. Let’s stop a no-deal Brexit – and let the people decide.”

Corbyn’s decision to set out his stall in favour of negotiating a Brexit deal and then putting that to a referendum presents a challenge to conference delegates over whether to back his stance or a more pro-remain position if it comes to a vote.

An effort to change Labour’s Brexit position will start on Saturday in Brighton, where delegates will discuss 80 motions submitted by local parties in favour of campaigning to remain in a second referendum.

After a process called “compositing”, one or two motions will emerge to be voted on by the wider conference later in the week. This may end up as a battle between largely remain-supporting activists and trade unions who favour Corbyn’s position, unless the two sides can agree on a compromise motion that avoids a public row.

A majority of the Brexit motions submitted have been put forward either by Another Europe is Possible (AEP) or two other groups, Labour for a Socialist Europe and Open Labour.

Michael Chessum, from AEP, said: “Labour has already crossed the Rubicon in promising a public vote with an option to remain. It would be utterly absurd, in those circumstances, for Labour not to campaign for remain when 90% of its members want to stay in the EU. Trying to prevent Labour from backing remain is a dead end for Corbyn – it will inevitably fail and it risks the morale of our base at at a crucial moment.”

Last week, Watson, the party’s deputy leader, used a speech to argue that Labour should “unambiguously and unequivocally back remain” and also seek a second Brexit referendum before a general election. The idea was swiftly rejected by Corbyn, who called it “Tom’s view”.

In his article, Corbyn promised that he would back a general election as soon as Boris Johnson’s threat of a no deal Brexit is avoided through an extension to article 50.

The issue of Brexit is likely to dominate Labour’s conference in Brighton but there will also be debate over the campaign pushing for the party to adopt a “Green New Deal”, involving a zero carbon target by 2030 and more green jobs.

Separately, the party’s national executive committee met on Tuesday to agree rule changes to speed up expulsions from Labour in serious cases of wrongdoing, which will be put to a vote at conference.

Jon Lansman, the founder of Momentum and a key Corbyn ally, won the NEC’s backing to effectively abolish its 40-year-old student wing, which is dominated by the more centrist side of the party. The motion said Labour Students was not officially affiliated and should be replaced, claiming it had not paid its fees. This was disputed by Rania Ramli, its chair.

The NEC also agreed to consider ways to speed up selections for parliamentary candidates in key seats. Some MPs believe this will lead to candidates being parachuted in from the centre rather than letting local parties decide in all circumstances, although proposals have not yet been worked up by party officials.