LONDON (AP) — Nervous "remain" supporters stepped up campaigning in Britain's European Union referendum Tuesday after odds on a vote to leave the bloc dramatically narrowed following a string of polls showing a surge in "leave" sentiment.

The pound fell to a two-month low against the dollar on Monday, to $1.4150, as bookmakers cut the odds of an exit vote in the June 23 referendum to as short as 6-5. "Remain" was still the favorite, but only just, after several phone and online polls released late Monday suggested growing support among voters for leaving the 28-nation bloc.

Senior Labour Party figures warned that leaving the EU could cause a recession and trigger big public-sector job losses.

Labour leader Jeremy Corbyn said trade unions across Europe had "bought us better working conditions, longer holidays, less discrimination and maternity and paternity leave."

"We believe that a Leave vote will put many of those things seriously and immediately at risk," he said.

"Leave" campaigners insist the government will have more money if it doesn't have to pay millions a week to the bloc.

The Rupert Murdoch-owned Sun tabloid urged its readers to vote for an EU exit, with a front-page editorial Tuesday under the headline "BeLeave in Britain."

The newspaper — which has a history of backing the winning side in elections — urged voters to reject a "dictatorial" EU that "has proved increasingly greedy, wasteful, bullying and breathtakingly incompetent in a crisis."

The Sun has seen its readership decline in the online news era, but it remains Britain's biggest selling newspaper, with a circulation of more than 2 million.

Meanwhile, a top EU official said "the world needs the European Union," in a remark seen directed at Britain ahead of next week's vote.

EU foreign policy chief Federica Mogherini has so far declined to comment on the referendum.

During Tuesday's opening of a two-day conference in Oslo, Norway on conflict mediation, Mogherini said the EU internationally is "strong voice for peace on our global stage," describing it as "a strong and honest broker in regional dynamics."

Mogherini said "the world needs also this kind of European Union," adding "it is sad to me to see that some European citizens have to be reminded of that from the outside."

Associated Press Writer Jan M. Olsen in Copenhagen contributed to this story.