Gordon Brown has acknowledged it is time for him to "adapt and rethink" Labour policy as he seeks to improve the party's prospects. Ahead of this month's annual Labour conference, which could prove decisive for his leadership, the Prime Minister also admitted the Government "must do more". His comments come after a summer of speculation about his position on the back of a series of election defeats and as Labour trails the Tories badly in the polls. Echoing his speech in Downing Street on the day he took over as Prime Minister 15 months ago, Mr Brown expressed his desire for change in "the way we govern". In a pre-conference article for The Monitor magazine, the premier stressed the economic challenges facing the UK were global in nature. He went on: "I believe that Britain is well placed to withstand the shocks that these transformations bring, but if we are to seize on the opportunities these new challenges present, then the country, the Government, and New Labour must do more. "Whether global or domestic, deep-seated or just fleeting, the pressures that we face in the short-term and the long-term have all changed since New Labour first came into Government. "And so, the way we govern must change too. That is why in Manchester this year it is time to adapt and rethink New Labour policy." Mr Brown described his determination to demonstrate he can provide the leadership required. The Prime Minister also acknowledged that improvements in social mobility under Labour have not matched expectations and had to be stepped up. Mr Brown's remarks come as Alistair Darling is due to meet with the Trades Union Congress in Brighton. Mr Darling will face debates on public services, education, and Britain's economic situation, while insisting the Government will not take unnecessary risks with the economy to provide short-term gains. Already there has been a programme of action over pay through striking and demonstrations. There are also calls for a windfall tax on energy companies, but Mr Darling will argue that a commitment to stability over the last ten years has enabled Labour to deliver record levels of employment, higher living standards and sustained investment in public services. Mr Darling will insist that Britain is well-placed to deal with global economic problems and say that while it is right that borrowing should be allowed to rise to support the economy, every Government must live within its means. The Chancellor will tell the conference: "Our purpose as a Government is fairness - to create a society where everyone has the opportunity to succeed, regardless of their background. "Sustainable growth, higher employment, better living standards, more investment in health, transport, housing and education are all essential if we are to build the fairer society we want to see." "We should not forget what together we have achieved over the past 11 years and that is why I am determined that we should not put those achievements at risk by taking unnecessary risks with economic stability. "A stable economy is not an optional extra - it is a means to an end: fairness, rising prosperity, opportunities for all."