pbr The main political parties are putting the finishing touches to their general election manifestos as they prepare for the first week of full-scale campaigning for the May 6 poll.br ppbr Labour will be first off the blocks with the launch in the West Midlands later of a manifesto which aides said will be "ambitious but affordable" and will focus on rebuilding the economy, renewing public services and restoring trust in politics.br ppbr The document's author Ed Miliband has acknowledged that Labour cannot "promise the earth" in Britain's current straitened circumstances, but said the party would reject a "business-as-usual" approach to the country's problems.br ppbr Speaking in east London on Sunday he said: "Above all it is a manifesto for the future because we know that business as usual won't do.br ppbr Meanwhile, David Cameron said the Conservative platform, to be unveiled on Tuesday, would be centred on the theme of "we're all in this together".br ppbr In contrast to Labour's restrained programme, the Tory manifesto will offer a range of "positive agenda-setting ideas" to woo voters, including better access to GPs and a crackdown on state "snooping", he said.br ppbr Liberal Democrat leader Nick Clegg has warned of Greek-style social unrest in the wake of the election if a Conservative government wins power by a narrow margin and then tries to push through draconian spending cuts.br ppbr The Liberal Democrat leader said he feared "serious social strife" if an administration with minimal support raised taxes, laid off public sector workers and froze wages.