The government has to respond to Sky's petition to make leaders' debates a permanent feature of UK elections.
The level of support means the government is required to respond to the petition, which was set up as part of Sky News' Make Debates Happen campaign.
The Leaders' Debate Commission would set the criteria for party participation, the objectivity of the audience, the debate formats and dates, plus the rules and the moderators.
Labour leader Jeremy Corbyn, Liberal Democrat leader Sir Vince Cable, former Green Party co-leader Caroline Lucas, ex-foreign secretary Boris Johnson and ex-home secretary Amber Rudd are among those prominent politicians to have already backed the campaign.
All SNP MPs have also given their support, while ex-deputy prime minister Nick Clegg, the Electoral Reform Society, former head of BBC News James Harding, businessman Theo Paphitis and Private Eye editor Ian Hislop are also in favour of an independent commission.
Following Sky News successfully lobbying for TV debates in the 2010 election campaign, three head-to-head clashes were held between Gordon Brown, David Cameron and Mr Clegg.
Since then broadcasters and politicians have failed to agree on terms and there were no head-to-head debates between the leaders of the main parties in the 2015 or 2017 general election campaigns.
Prime Minister Theresa May, who did not appear in any televised debates prior to last year's snap general election, has refused to say whether she backs the campaign.
She told Sky News: "The next general election isn't until 2022. There's plenty of time to think about those issues at that time."
If the petition goes on to reach 100,000 signatures by 21 March next year, it will be considered for a debate in parliament.
Sky News' editor-at-large Adam Boulton said: "I think there is real enthusiasm behind the debate. I think the danger is complacency, yes of course they should happen, people think why wouldn't they happen.
"There's no doubt the Labour Party would love to see Jeremy Corbyn up against the leader of the Conservative Party.
"With newspaper headlines saying we could have a general election this autumn, there really is no time to lose. It does need a wave of public support to convince the politicians to take the next step."