Corbyn told his party’s lawmakers that Labour “will do everything in our power” to prevent Britain from leaving the EU without a deal.

Labour Party leader Jeremy Corbyn addresses a rally in Broxtowe, central England on Feb. 23, 2019.Oli Scarff / AFP – Getty Images

SHARM EL-SHEIKH, Egypt — Britain’s main opposition party took a big step Monday toward backing a second Brexit referendum amid intensifying concerns the country could crash out of the European Union next month without a deal.

The Labour Party did not specify what voters might be asked to consider in any future vote, though it has previously said the option of Britain remaining an EU member would be included.

However, the party’s latest position on the question has the potential to alter the course of Brexit a little more than a month before the scheduled withdrawal day.

The EU warned Britain it faces the prospect of delaying its planned March 29 departure or the consequences of a chaotic exit. European Council President Donald Tusk, who chairs meetings of EU nation leaders, said Monday it would be “rational” to postpone Brexit day.

Labour has proposed its own withdrawal plan as an alternative to the government’s deal with the EU. The party said Monday it would back a second public vote if the House of Commons rejects its plan this week, as is widely expected.

Labour’s Brexit plan envisions far closer economic ties between Britain and the EU than the agreement Prime Minister Theresa May negotiated, which lawmakers overwhelmingly voted down last month.

Leader Jeremy Corbyn told Labour lawmakers the party “will do everything in our power” to prevent Britain leaving the EU without a deal on the country’s withdrawal and on the outlines of its future relationship with the remaining 27 members.

But Corbyn also said Labour would oppose any agreement based on the “overwhelmingly rejected” deal that May is trying to resuscitate.

As a result, Labour plans to put forward or support an amendment in Parliament “to prevent a damaging Tory Brexit being forced on the country,” he said.

Voters narrowly approved the June 2016 referendum to pull Britain out of the EU. Labour has said it would only support a second referendum as a last resort if it could not secure a new general election or make changes to May’s divorce deal.

The party leadership has been reluctant…