Poll highlights uphill struggle for Conservatives The premier has quietly dropped his support for new garden cities More than a third of voters who supported UK prime minister David Cameron in the 2010 election would not vote for his Conservative party if an election were held tomorrow. The opinion poll finding, which highlights the uphill battle facing the Conservatives in 2015, comes from Lord Ashcroft's latest round of research on the party's electoral prospects. The former Conservative party Treasurer and pollster warns Downing Street that it must attract a "bigger coalition of voters" if the party is to have any hope of governing after the next election. The polling found that 37 per cent of 2010 Conservative voters - dubbed "defectors" - would not support the Tories in an election tomorrow. Half of those said they would shift their support to the eurosceptic UK Independence Party. The defectors significantly outweigh new supporters - "joiners" - making it more difficult for Mr Cameron to win in 2015. Only six per cent of those polled were joiners. Twenty-three per cent said they would stick with the party in 2015. "An overall majority looks as elusive as it has throughout parliament," wrote Lord Ashcroft in his research, which was published on Saturday. To win one, the Tories needs the votes of everyone who supported them last time, plus everyone who is even prepared to think about doing so the next time. Unfortunately, a lot of people in the first group are not currently in the second. However, Lord Ashcroft urged the party not to be distracted from the task of winning new voters by the Ukip threat in the run-up to the European elections in May. Pundits will be preoccupied by how well Ukip do, and at what cost to the Conservatives. But the Tories must keep their eye on the prize. Whatever tactical moves they make to minimise losses in an election that many people regard as inconsequential - and therefore an opportunity to cast a cost-free protest vote - must not be at the expense of building a coalition of voters that could give them a majority at Westminster. An overall majority looks as elusive as it has throughout parliament Lord Ashcroft Mr Cameron has in recent months sought to counter the Ukip threat by appealing to more traditional Conservative voters with promises of an EU referendum in 2017, a tax break for married couples and with his tough rhetoric on immigration. But modernisers such as Andrew Cooper, No 10"s former director of strategy, are adamant that the prime minister must not retrench to core-Tory territory and instead try to attract younger, urban and ethnic voters to build support for the future. Lynton Crosby, the Tory election chief, wants the party to concentrate on just two messages: the economic recovery and the choice between Mr Cameron and Ed Miliband, the opposition leader, as the next prime minister. Lord Ashcroft's research found that 57 per cent of 8,000 adults polled trusted Mr Cameron and chancellor George Osborne to manage the economy, against 43 per cent for Mr Miliband and Ed Balls, the shadow chancellor. Thirty two per cent said they were dissatisfied with Mr Cameron but preferred him to Mr Miliband; 40 per cent said they would prefer to see the Labour leader in power.