Lib Dem leader Tim Farron, UKIP's Paul Nuttall, SNP deputy leader Angus Robertson, Green co-leader Caroline Lucas and Plaid Cymru leader Leanne Wood are all due to participate in the BBC debate this evening.
But with Corbyn holding his own during the Sky News/Channel 4 "Battle for Number 10" programme and Labour closing in on the Tories in the opinion polls, he has thrown his hat in the ring with just over a week to go before the 8 June vote.
In the debate, which will be shown live at 7.30pm on BBC One, the Conservatives will instead be represented by Amber Rudd, the home secretary, who performed strongly in a similar encounter as a Remain campaigner ahead of the European Union referendum.
Seeking to put behind him Tuesday's childcare gaffe in which he struggled to recall the cost of his own policy in a BBC radio interview, Mr Corbyn will have been buoyed by the latest YouGov poll that suggested the United Kingdom could be heading for a hung parliament on 9 June, with the Tories falling short of an overall majority.
He challenged May to join him on Wednesday, saying "we must give people the chance to hear and engage with the leaders of the main parties before they vote".
Asked several times by reporters during a campaign event in southwest England why she was not taking part in the debate, May said she prefered to spend time meeting voters.
He also criticised the Tories for what he called "a stage-managed arms-length campaign".
The Labour leader replied: "Well, I'm afraid I can't really answer that".
"Refusing to join me in Cambridge tonight would be another sign of Theresa May's weakness, not strength".
Labour has said it will invest £37bn in the NHS and £8bn in social care by the end of the next parliament if it wins the election.
"I think anyone that trusts polls at the moment is naive to say the least", she said. We will cut class sizes, take a million people off the NHS waiting list and ensure people get the care they deserve.
The debate will be followed on Friday with a Question Time special.
Broadcast live on BBC 1, the debate will be moderated by BBC News presenter Mishal Husain, a Cambridge alumna.