<p><br /> David Cameron has sought to renew focus on Labour's plan to raise National Insurance with fresh visits to firms whose bosses have publicly backed his pledge to reverse the "tax on jobs".<br /> </p><p><br /> As Gordon Brown prepared to launch Labour's manifesto, the Tory leader was at a builders' merchant in the Tory target Reading West constituency in Berkshire to talk to staff about his party's plans.<br /> </p><p><br /> A promise to reverse the bulk of the 2011 NI increase - paid for with £6 billion of immediate efficiency savings - will be at the heart of the Conservatives' own manifesto.<br /> </p><p><br /> Political opponents have dismissed the "fantasy" savings figures and warned it will inevitably mean severe public spending cuts or a rise in other taxes such as VAT.<br /> </p><p><br /> But the move has been backed by more than 150 prominent businessmen who have now signed an open letter, sparking a spat with Labour ministers who accused them of having been "deceived" by the Tories.<br /> </p><p><br /> More details are emerging of policies to be included in the Tory manifesto, including a promise to consult on a scheme to cushion the blow of oil price rises for motorists at the pump.<br /> </p>
