Jeremy Corbyn has proposed a crackdown on the "influx of big money into politics" as he accused the Conservatives of being captured by donors who are "corrupting democracy".
The Labour leader said his party would ban donations or loans to political parties from those not registered for tax in the UK.
Mr Corbyn told a rally in Bolton that "politics should work for the millions, not the millionaires" on Saturday evening.
Labour analysis of the Register of Members' Interests suggested Prime Minister Boris Johnson has received £953,056 in donations and income from "hedge funds and bankers" over the last 15 years.
The figure includes contributions to him or the Conservative Association in his constituencies of Henley and Uxbridge worth £720,000, while speeches to banks in Europe and the US led to him receiving a further £233,056.
Mr Corbyn said: "People are right to feel that politics doesn't work for them.
"It doesn't. Boris Johnson and the Conservative Party are captured by big donors, who are corrupting democracy.
"If you have the money you can get access to ministers.
"Look at the fracking industry.
"But if you wish to protest against the frackers because it will damage the environment, you can't get a hearing.
"We have to stop the influx of big money into politics. Politics should work for the millions, not the millionaires.
"Labour is the party of the many, not the few and we do things very differently.
"We are funded by workers through their trade unions and small donations, averaging just £22 in the last general election.
"That's why we will be able to drive big money out of our democracy."
He added: "So today, I'm announcing that we will ban donations or loans to political parties from people who are not registered for tax in the UK, so are not contributing to our public services and infrastructure.
"Our shadow minister for the Cabinet Office, Jon Trickett, has been working on a comprehensive plan to stop big money buying up our democracy, and to empower people and communities, and will outline further plans in the autumn."