Tory policy chief David Cameron has warned voters "don't know enough, if anything at all" about what the party would do in power.
Speaking at a fringe meeting at the party's annual conference in Bournemouth, Mr Cameron warned of a
"wall of cynicism" among voters.
He said the Tories had to modernise or they were "dead".
And he cautioned against becoming a one issue party by focusing too much on areas like Europe.
"If you don't understand the complexities and changing nature of modern society you are irrelevant," he said.
Mr Cameron said that voters wanted political parties to tackle the broad range of issues that they care about".
"In the main that means schools, hospitals, crime, immigration and the economy," he said.
"If you don't sound balanced, you won't seem balanced."
Vision of society
Mr Cameron also warned against his party being "exclusively negative", adding that there were three questions that mattered in terms of political success.
"Do people share your values? Do they agree with you about what's wrong? And do they think you have the right plans for doing something about it?" he asked.
Mr Cameron stressed that his party's vision of society was one in which people met their obligations to each other and that there was a "net beneath which no one should fall".
"That there is a 'we' as well as a 'me'," he added.
Speaking at the same meeting, Tory deregulation spokesman John Redwood said Europe, immigration and tax cuts should be central to the party's pitch to the electorate at the next election.
On the day shadow chancellor Oliver Letwin told representatives he was not ready to make any firm tax cutting pledges, Mr Redwood said Conservatives should make it clear "we are again the tax-cutting party".
On Europe he said Michael Howard would renegotiate the party's relationship with Brussels.
Former Foreign Secretary Sir Malcolm Rifkind said the Tories should be aiming not for the unprincipled centre ground but for the "common ground" of shared principles with ordinary people.