Labour electoral victory might come sooner than 2020, Jeremy Corbyn claimed, as he raised the prospect of an early general election.
The Opposition leader set out plans to revolutionise the way the economy is run and suggested the party may be able to implement them earlier than expected.
Under rules introduced by David Cameron the next national poll will not be held for four years, but Mr Corbyn suggested the Government - currently riven by deep divisions over Europe - could collapse before then.
He said: "It's how we make policy in this party that will lead us through to an electoral victory at some point in the future.
"You never know, it might be sooner than 2020, who knows?"
At a Labour State of the Economy conference in central London, Mr Corbyn said wealth creation is a "good thing" but insisted there must be a "serious debate" about how it is "shared".
He said: "Labour will always seek to distribute the rewards of growth more fairly but, to deliver that growth demands real change in the way the economy is run, change that puts the interests of the public, the workforce and the wider economy ahead of short-term shareholder interest.
"Wealth creation is a good thing: we all want greater prosperity. "But let us have a serious debate about how wealth is created and how that wealth should be shared."
John McDonnell told the conference that Labour helped to create an "unfair tax system" when it was in power.
The Shadow Chancellor said too many institutions at the heart of the British economy were "not fit for purpose".
Labour will revive plans for rent controls and urge councils to follow the lead of areas like Manchester to offer cheap, local authority-backed mortgages, the conference was told.
"Labour would make it a mission to ensure families and young people on ordinary incomes aren't locked out of home-ownership as they are under the Tories, he said.
Labour under Tony Blair and Gordon Brown did not do enough to tackle tax-dodging, he added.
"The old rules meant the last Labour government relied too heavily on tax revenues from financial services, and too heavily on off-balance sheet spending through the Private Finance Initiative," he said.
"It didn't do enough to clamp down on tax evasion and avoidance. It helped create an unfair tax system."
Mr McDonnell said there was a "fixation" in big business with shareholder value and criticised corporations for "hoarding" cash and paying chief executives "obscene" amounts.
Labour last year launched a review into the Treasury, HMRC and Bank of England that will lead to reforms in the way they operate if the party takes power, he said.