Campaigning in Britain's most unpredictable election in a generation entered its final day with the two main parties level in most polls and neither on track to command a majority in parliament. Despite five weeks of campaigning, neither Prime Minister David Cameron's Conservative Party nor Ed Miliband's opposition Labour Party has a clear lead.The stakes are high because of a rare confluence of factors that puts Britain's future in the EU, and its national cohesion, in jeopardy.Cameron has promised to hold a referendum on whether to stay in or quit the EU if he is returned to power. And polls suggest that the Scottish nationalists could emerge as the third-biggest party, despite losing a referendum last year on whether Scotland should break away from the UK."The consequences if you take a wrong turn could, at their worst, mean that, within a matter of years, two unions which are pivotal to the prosperity and way of life of everybody in Britain are lost," Nick Clegg, the deputy prime minister and Liberal Democrat leader, warned the electorate.Five years ago, Britain got its first coalition government since World War2 when Cameron fell short of an overall majority and struck a deal with Clegg's centrist party to govern together to steady the economy.But the rise of fringe parties such as the pro-independence Scottish National Party and the anti-EU United Kingdom Independence Party (Ukip), which has spent much of the campaign fending off accusations of racism, has drained support from the two main parties.A TNS opinion poll yesterday underscored how close the contest is, putting the Conservatives one point ahead of Labour, indicating that neither of the major parties will win an overall majority in the 650-seat parliament.Cameron, who is banking on one of the strongest economic recoveries in the developed world to get him re-elected, was making his final pitch to voters yesterday.Stagnant polls have prompted him to refine his message, blending the promise of higher living standards with a warning that Scottish nationalists could hold to ransom a minority Labour government, forcing it to borrow more and edge towards Scottish independence.Awkwardly for the prime minister, a leading think tank yesterday cut its forecast for Britain's economic growth this year, though it said strong consumer spending should keep the recovery on track.Labour's Miliband was to speak at a final rally in northern England last night."This is the choice at the election: a Labour government that will put working people first or a government that will stand up only for a privileged few," he will say...