By Estelle Shirbon
LONDON (Reuters) - Groups campaigning for Britain to leave the European Union have pulled ahead of those urging Britons to remain in the bloc in the race to raise funds, the Electoral Commission said on Thursday.
The various groups on the "Out" side received a total of 3.8 million pounds ($5.6 million) in donations between April 22 and May 12, more than double the combined 1.6 million pounds received by groups campaigning for "In", new data showed.
Britons will vote on June 23 on whether to remain in the 28-member EU, the world's largest trading bloc, a choice with far-reaching consequences for politics, the economy, defense and diplomacy in Britain and far beyond.
Opinion polls have given conflicting steers on which way the referendum might go, with telephone polls suggesting "In" is comfortably ahead while online polls suggest a tight race that "Out" could win. Betting odds heavily favor an "In" vote.
Some analysts say that the "Out" side may be benefiting from higher engagement among its supporters, many of whom are implacably opposed to the EU, while the "In" side is defending a status quo seen as safe but uninspiring by many voters.
"(The donations data) suggests that the 'Leave' side, as we would expect, are better at mobilizing their supporters and getting them to dig into their pockets," said Pawel Swidlicki, policy analyst at independent think-tank Open Europe.
"But they also have to work a lot harder to win."
The official government position is that Britain should vote to stay in the EU. There have been Treasury reports warning of the negative impact of leaving, and a government leaflet in favor of "Remain" that cost 9.3 million pounds to produce and distribute to every household in Britain.
But the "Out" camp has consistently raised more funds.
In the 12 weeks from Feb. 1, "Leave" groups had received 8.2 million pounds in donations, mainly from investment firm founder Peter Hargreaves and insurance tycoon Arron Banks, compared with 7.5 million pounds in donations for their "Remain" rivals. Banks also lent campaign group Leave.EU 6 million pounds.
Thursday's new data showed the official Vote Leave campaign was now by far the biggest single recipient of donations, with 3.4 million pounds to add to its war chest -- welcome news for Vote Leave, which trailed rival Leave.EU in the previous period.
Vote Leave counts former London mayor Boris Johnson and cabinet minister Michael Gove among its leading campaigners, while Leave.EU backs Nigel Farage of the anti-EU party UKIP.
Led by Prime Minister David Cameron, the "In" camp has been endorsed by foreign leaders including U.S. President Barack Obama, and by the likes of the International Monetary Fund.
The official "In" campaign, "Britain Stronger In Europe", received 1 million pounds in donations between April 22 and May 12. "Remain" donors have included David Sainsbury, the former chairman of the supermarket Sainsbury's, and investment banks.