By Kylie MacLellan
LONDON (Reuters) - Eurosceptics who want Britain to quit the European Union are letting pro-EU campaigners get a head start in mobilizing opinion ahead of an In/Out referendum that could take place within a year, Britain's most prominent Eurosceptic said on Thursday.
Prime Minister David Cameron, buoyed by an unexpectedly decisive election win in May, has already begun trying to renegotiate Britain's relationship with the EU, saying he will campaign for a 'Yes' to continued membership if the talks are successful.
Nigel Farage, leader of the anti-EU UK Independence Party (UKIP), said high-profile interventions such as U.S. President Barack Obama saying he wanted Britain to stay in the EU, and the launch of pro-EU campaign groups such as Universities for Europe, had left the 'No' side lagging.
While there have been reports of 'No' campaigners planning launches, and some of Cameron's Conservative lawmakers have formed a group that will push to leave if he does not secure major changes, there has been little public campaigning for the 'No' side, and no figurehead has emerged to lead it.
"There is no doubt at all that the 'Yes' side are in the lead," Farage said. "We cannot allow Cameron to go into this renegotiation unchallenged, we cannot allow the 'Yes' side to have the massive head start they have got."
Cameron has promised to hold the referendum no later than 2017, and last week the Independent on Sunday said he had penciled in a date next June.
In a poll of 5,000 people by Survation published on Thursday, 45 percent said they planned to vote to stay in the bloc, 37 percent wanted to leave and 18 percent were undecided.
UKIP polled 12.6 percent in May, but many Eurosceptics say its leader is too divisive to take a prominent role in the 'No' campaign.
Farage said he would not seek to head the official 'No' campaign, and hoped someone from business or sport would do so.
He also said he would "obviously" step back if his involvement appeared to be damaging the 'No' vote, but at the moment he was "probably better than no one".
From September, UKIP plans to use its network of local branches and members to host hundreds of public meetings across the country to urge a departure from the EU, Farage said.
"I am also urging those in other campaigns who seem to think it is better to wait until the prime minister comes back from his renegotiation ... that this is a terrible mistake, that we are giving the prime minister a big head start in this and that is the wrong approach," Farage said.
"The whole Eurosceptic movement needs to do two things: 1) get cracking, and 2) come together."
(Editing by Andrew Osborn and Kevin Liffey)