Thirty five of the UK's leading businessmen have urged chancellor George Osborne not to backtrack on his pledges to cut public spending or the country will face higher taxes and interest rate rises.In a letter to the Telegraph, the businessmen said it would be a "mistake" to water down his proposals."Addressing the debt problem in a decisive way will improve business and consumer confidence. Reducing the deficit more slowly would mean additional borrowing every year, higher national debt, and therefore higher spending on interest payments," the letter said.The cost of delay would result in almost £100bn of additional national debt by the end of this parliament alone, the signatories claimed, adding they were confident the private sector would take on public sector staff who lose their jobs."The private sector should be more than capable of generating additional jobs to replace those lost in the public sector, and the redeployment of people to more productive activities will improve economic performance, so generating more employment opportunities," the letter added.The 35 signatories to the letter included Andy Bond, the chairman of Asda, Gordon Frazer, the managing director of Microsoft UK, Ian Livingston, the chief executive of BT, and Charles Dunstone, the chairman of Carphone Warehouse.George Osborne will unveil his £83bn programme of cuts and revenue raising measures on Wednesday in a comprehensive spending review.