Brown's speech, excerpts of which were released in advance, touches on core issues for Labour supporters, such as boosting education for poor children and care for the elderly. He plans to unveil a $557 million fund to offer home Internet access to around 1 million poor British families.
Brown will also sketch out a government agenda promising jobs, training and welfare - but asking the public to work hard and abide by laws in return.
"We will create rules that reward those who play by them and punish those who don't. That's what fairness means to me," Brown planned to say, according to the excerpts.
A message of support from Democratic U.S. presidential candidate Sen. Barack Obama was to be played Tuesday on screens across the convention center in the northern England city of Manchester.
Brown has faced back-to-back challenges since replacing ex-leader Tony Blair in June 2007. His party has slumped to almost unprecedented low ratings, has been beaten badly in a series of special elections and lost control of London's City Hall.
Analysts predict the Labour Party will lose the next national elections - which must be called by mid-2010.
Party dissidents have urged Brown to quit, and one junior minister resigned last week rather than continue to support Brown.
But Brown's prospective challengers have held their fire during the five-day party convention. Instead, they are pledging loyalty at a time of economic turmoil.
And Brown - who was Treasury chief for 10 years under Blair - plans to capitalize on his experience in hopes of winning back support.
Foreign Secretary David Miliband, regarded as Brown's most likely successor, said Brown would rally party activists with a rousing speech Tuesday.
"He's a leader with really deep values and real sense of were the country needs to go and I think we'll see that today," Miliband told The Associated Press.
Blair's ex-deputy John Prescott said he was sure Brown would quash any rebellion.
"He's the best man to deal with the kind of global problems we've got," he told the AP.
However, even a standout address might not be enough for Brown to save his job, with a tricky special election pending in Scotland and new battles ahead over unpopular terrorism laws.
The rising prices of gas, food and fuel have dented public confidence in Brown. Britons are also worried by falling house prices, rising inflation and predictions that the U.K. economy is tumbling toward recession.
"We need someone else in power because he's not doing very well," Phil Woolley, a 25-year-old voter in Manchester's Cheetham Hill district, said Monday.
But Brown has won some important new backing, including a $1.85 million donation to party funds from "Harry Potter" author J.K.
Rowling.
Australia's Labor Party Prime Minister Kevin Rudd paid glowing tribute to Brown in a video played to delegates Monday. Brown has the ability "to deal with the great challenges of our age," Rudd said.
Sardar Khan, a 42-year-old unemployed security guard from Manchester, said he believed the Labour Party should rally behind Brown.
"He deserves more sympathy and support, especially from his party. The economic problems are America's fault, not his, and he shouldn't be blamed for them," Khan said.
