Sir Keir Starmer has said Labour could negotiate "a new single market relationship" with the EU after Brexit.
The shadow Brexit secretary said options for retaining the benefits of the single market and customs union "should not be swept off the table", as he also mentioned a new bespoke trade deal.
Sir Keir told the party's conference Labour would negotiate a deal "that retains the benefits of the customs union and the single market".
He said: "Options for achieving that end should not be swept off the table. Subject of course to negotiations, remaining in a form of customs union with the EU is a possible end destination for Labour.
"We are also flexible as to whether the benefits of the single market are best retained by negotiating a new single market relationship, or by working up from a bespoke trade deal. The outcome is what matters."
He said Labour would not have "no rash, ideological red lines preventing a sensible deal".
He added: "No fantastical 'blue sky' proposals. A pragmatic approach. Labour are now the grown-ups in the room. We stand ready to take charge of the negotiations. Not acting for narrow political gain, but in the national interest."
Labour would remain in a customs union and the single market during any transitional deal - a stance that has now been adopted by the Government, said Sir Keir.
"Let's see if that survives contact with Tory Party conference next week," he added.
Sir Keir also said Labour would negotiate a deal that will ensure continued co-operation in all fields with EU partners.
He also said that Labour is "ready to take charge of the negotiations" and deliver a "sensible" Brexit that respects the result of the referendum.
The Labour leadership is under pressure to commit the party to staying in the single market and maintain free movement after Brexit.
Sir Keir said: "The way the Tories are handling Brexit tells you a lot about their competence - or should I say incompetence. But it also tells you about their character. About their dogmatic disregard of the national interest. About their sheer sense of entitlement, about their post-imperial delusions, about their willingness to put other people's jobs at risk."