Britain will vote on whether to remain in the European Union on Thursday, June 23, Prime Minister David Cameron has said.Cameron made his announcement in Downing Street after briefing the cabinet, BBC reported.Cameron would campaign to remain in a reformed EU. He described the vote as one of the biggest decisions "in our lifetimes".A string of ministers have come out in favour of remaining -- but others will campaign against Cameron.Cameron warned that leaving the European Union would be a "leap in the dark" as he urged voters to back his reform deal.Home Secretary Theresa May heads the list of those who have announced they will campaign to stay -- but Justice Secretary Michael Gove has signed up to the leave campaign.Leave campaigners also hope London Mayor Boris Johnson will join their cause -- but he has yet to declare where he stands.Cameron claims his EU reform deal -- hammered out at a two-day summit in Brussels -- will give the Britain "special status" within the bloc -- tackling concerns over migrants getting "something for nothing" from the benefit system and exempting the country from the EU drive for "ever closer union".Critics said it does nothing to tackle high levels of immigration or take back powers from Brussels, with UKIP leader Nigel Farage branding it "truly pathetic".