David Cameron said he would fight on a message of 'hope, optimism and change' Tuesday as he launched the Conservative Party's general election campaign that could see him become Britain's prime minister. The Tory leader, whose party is ahead in the opinion polls, said the May 6 election was the most important in a generation, as he pledged to offer an exciting, radical alternative to Prime Minister Gordon Brown. 'Let me tell you what I think this election is all about,' he told cheering supporters at County Hall in central London. 'It is about the future of our economy, it's about the future of our society, it's about the future of our country. 'It's the most important general election for a generation. It comes down to this: you don't have to put up with another five years of Gordon Brown,' he added. The 43-year-old said there was a 'modern, Conservative alternative that is about voting for hope, voting for optimism, voting for change. 'This country deserves a lot better than five more years of Gordon Brown and that is what we must offer. 'So let's get out there and say 'Let's get off this road to ruin and instead get on the path to prosperity and progress'. 'Let's fight for what we believe in. Let's take the case to the country, to the people of this country, about hope, optimism and change. And let's win this election for the good of the country that we love.' Cameron took over from Michael Howard as Conservative party leader in December 2005 and set about overhauling the party to make it more representative of modern Britain. The Conservatives have been in opposition since losing the 1997 general election under prime minister John Major, a landslide defeat that saw the Labour Party sweep into office under Brown's predecessor Tony Blair. 