Jeremy Corbyn faced a backlash from across his party at Labour conference for advocating a Brexit that leaves the UK outside the single market.
The Brighton gathering was shaping up to be a celebratory one for the leader, who headed to the seaside town emboldened by a strong general election performance.
But he came under increasing pressure from MPs, activists, unions and protesters to commit the party to staying in the single market permanently.
Left-wing MPs were among 30 senior figures who signed a letter in the Observer demanding the party declares its backing for full membership of the free trade area, while “ruling out no options for how to achieve this”.
Ian Murray MP, the former Shadow Scottish Secretary, and the long-serving MEP David Martin were among the signatories.
Separately, three Scottish branches called for the party to adopt that position as official policy.
In an interview with the Andrew Marr Show, Mr Corbyn said he would listen to the 66% of the party’s members who want to stay in the single market.
He said he wants to retain access, as opposed to full blown membership, to the trade zone to ensure “tariff-free access to the European market”.
But he warned: “I would also say that we need to look very carefully at the terms of our trade relationship, because at the moment we are a part of the single market and that has within it restrictions on state aid and state spending and pressures on it, through the European Union, to privatise rail and other services.”
Mr Corbyn has been trying to appease voters who want to the stay in the single market, as well as those who backed Leave to reduce immigration.
The European single market enables trade without barriers, but comes with the free movement of people between states as non-negotiable condition.
In a fringe event, Shadow Brexit Secretary Keir Starmer said other models are available for achieving the benefits of the free trade other than through full membership.
Chuka Umunna, pro-EU Labour MP, acknowledged he had been a “pain in the arse” to Sir Keir but said “we need to go further still” and campaign to stay in the single market permanently.
In a separate event, Clive Lewis, who was in Corbyn’s shadow cabinet, said opposition to freedom of movement with the EU is being driven by racism.
One Labour member, who was armed with a placard “stop crazy Brexit now” outside the conference venue, said he felt “abandoned” by the party for refusing to fight departure from the bloc – and would back the the Lib Dems in the future.
Liberal Democrat leader Sir Vince Cable said: “Jeremy Corbyn has always wanted to leave the EU, leave the single market and leave the customs union.
“Now he is pulling out his old anti-EU arguments to defend Labour’s endorsement of Brexit.”