Thousands of people are set to march on central London in a national anti-austerity demonstration.
Slogans such as Cameron Must Go - Tories Out! and demands for decent Health, Homes, Jobs And Education are expected to be brandished on the march, which counts trade unions and campaign organisations among its supporters.
Campaigners hope the march, organised by the People's Assembly, will be a "critical moment" for the government, which has faced growing pressure over issues including the future of the beleaguered steel industry and the continuing dispute over junior doctors' contracts.
Shadow chancellor John McDonnell, who is set to join demonstrators at Saturday's event, said that "people need to show their opposition".
People's Assembly National Secretary Sam Fairbairn said: "Enough is enough. We simply cannot afford the rich any longer. As they amass and hide their wealth on an industrial scale, we are seeing our NHS face its biggest financial crisis in its history, jobs being shredded in the steel industry and ordinary people facing massive attacks on their standard of living."
Activists have further been spurred on by the revelations in the Panama Papers leak regarding offshore companies.
In a rallying call to its supporters the People's Assembly tweeted: "We are all set for the Big One", and said they would "See you on the streets!!"