Britain, which has a budget deficit forecast to be $266bn for the current fiscal year, emerged from recession in the fourth quarter of last year with growth of 0.3 per cent.
The expansion in October to December 2009 followed a deep recession that lasted six quarters, the country's longest since records began.
In his speech to business leaders at Thomson Reuters in London, Brown said that the economy was "at a turning point and a crossroads".
"For better or for worse, with me what you see is what you get. The stakes are high. We dare not risk the recovery," he said.
"There will be bumps in the road. And I believe the only way to overcome them is by displaying the same strength and resolve as we did during the crisis. And I will not let you down."
David Cameron, the opposition Conservative leader, has long held a double-digit lead in opinion polls but Labour has clawed back ground since Britain emerged from the recession, promising a close fight in the election.
The Conservatives are four points ahead of Brown's Labour Party according to the Sun newspaper's latest daily opinion poll on Wednesday.
The poll showed Cameron's party on 36 per cent, down three per cent, Labour on 32 per cent, down two per cent, and the Liberal Democrats on 20 per cent, up four per cent.
YouGov questioned 1,524 people for the poll on March 8 and 9.
Experts say the Conservatives need a bigger lead than that to secure an overall majority in the House of Commons, raising the prospect of a rare hung parliament in Britain for the first time since 1974.
In his speech, Brown appeared to contrast himself with Cameron, 43, who has never held ministerial office and who the prime minister accuses of lacking experience, saying that questions of "policy" and "character" were closely linked.
"I believe that character is not about telling people what they want to hear but about telling them what they need to know," he said.
"It is about having the courage to set out your mission and the courage to take the tough decisions and stick to them without being blown off-course, even when the going is difficult."
Cameron is campaigning on a "time for change" slogan and wants to make a quicker start on cutting a deficit forecast to exceed 12 per cent of GDP this year.
Experts said it was now all but certain that the election date would be confirmed by Brown in the days after the budget, leading into a campaign lasting five weeks or a month.
"I would be astonished if it's anything other than May 6," said Peter Kellner, president of YouGov.