Britain’s main opposition Labour Party leader, Jeremy Corbyn, has called for a second Brexit referendum if Prime Minister Theresa May fails to finalise a close economic partnership with the European Union.

After presenting EU officials with Labour’s proposals on February 21, he stressed the need for a customs union to build a Commons majority for the Brexit deal.  He told reporters his plan is “credible”.

As reported by the Guardian, Corbyn had proposed last month for the Commons to vote on two options – its alternative Brexit plan and whether to legislate “to hold a public vote on a deal”.

Speaking in Brussels, he said that the option of a second vote would remain key to Labour’s strategy.

“We will put a motion to parliament, as I have already,” Corbyn said. “Keir Starmer and I have put a motion to parliament, which included the option of a popular vote to confirm otherwise agreements that have been reached. That was rejected by parliament at that stage. Clearly it is very much part of the agenda put forward by the Labour party.”

Corbyn also said May was “running down the clock” in the negotiations.

“We put forward what we believe to be a credible process which would be to negotiate a customs union with the EU and alignment to ensure market access,” he said. “We are strongly of the belief that these proposals are credible. That has been confirmed by our meetings today. The problem is the prime minister is insisting on her deal which has already been defeated very heavily in Parliament and running down the clock by trying to keep the threat of no deal on the table with all the damage that does.”