Jeremy Corbyn is to unveil his blueprint to "rebuild" Britain before going head-to-head with Owen Smith in the campaign's first Labour leadership showdown.
The incumbent leader is expected to outline 10 pledges aimed at detailing how the country can respond to its "broken" economic model when he campaigns in east London.
Frontrunner Corbyn will later travel to Cardiff for a live debate with Smith, who has warned he is "deeply worried" the Labour Party is going to split.
The Islington North MP's pledges come a day after Smith laid out a radical programme of reform which he said would amount to the "biggest boost to living standards for a generation".
A "triple-lock" that includes a pensions overhaul, changes to benefits and a higher minimum wage were among Smith's proposals.
But Corbyn is expected to claim everyone can have "richer" lives and detail how he believes he can transform the country alongside the party.
In a speech in Dagenham, east London, Corbyn is expected to say: "There is immense potential in the skills and talents of our people and huge opportunities ahead of us in science, technology and culture.
"We could all be living richer lives in a sustainable, more prosperous and more caring society. Labour will pledge to rebuild and transform Britain with a bold £500 billion programme of investment.
"We will deliver the transport and communications infrastructure a modern economy needs, not just in those places where the economy already works but right across the whole country."
"We will back this up with new institutions able to deliver the investment our communities so desperately need.
"A new £250 billion national investment bank, backed up with a network of regional development banks, will put power to determine their own futures back into the hands of those places outside of Westminster and the City of London."
Corbyn has previously laid out a series of pledges aimed at ending "rip-off Britain" and tackling "injustices" in the workplace, including the banning of zero-hours contracts, increasing the living wage and repealing the controversial Trade Union Act - which places restrictions on strike ballots.