The Prime Minister has been accused of snubbing young voters after his office said he would not take part in a series of live Q&A sessions with party leaders organised by Bite The Ballot together with ITV News.
Labour leader Ed Miliband, Deputy Prime Minister Nick Clegg, Ukip's Nigel Farage and the Green Party's Natalie Bennett have all appeared on previous Leaders Live events.
Bite The Ballot accused Mr Cameron of "pulling out" of the event and has started an online campaign using the #WeWantMore hashtag.
ITV News understands that Downing Street is now considering whether Mr Cameron could fit in the debate on an alternative date.
The decision comes after months of negotiations with Bite The Ballot during which time David Cameron's office indicated that he was keen to take part.
In a timeline detailing these negotiations on its website, Bite The Ballot says it received notification yesterday indicating that Mr Cameron will “not be able to participate".
Bite The Ballot's managing director Michael Sani told ITV News he felt that the political campaign group had been "led up the garden path":
Despite struggling to settle on a date, Downing Street has denied that Mr Cameron pulled out from doing the show.
A Tory source quoted by the Press Association news agency said the Prime Minister "never gave them a firm commitment" and that there were simply "no dates that would work".
In response, Bite The Ballot released this letter dated from August 2012 in which the Prime Minister appears to throw his support behind the campaign:
The news comes just a day after Mr Cameron said he would not join the televised election debates in their proposed format.
In an exclusive interview with ITV News, he said he objected to the proposal to exclude the leader of the Green Party, Natalie Bennett, who incidentally appeared in the first Leaders Live Q&A.
Several celebrities and prominent YouTubers who have taken part in previous Leaders Live events expressed their anger, including singer Eliza who spoke to ITV News:
Others took to Twitter to invite Mr Cameron to change his mind:
Leaders Live is the nation's first series of live streamed Q&As that aims to engage directly with young voters.
The series, organised by Bite The Ballot and hosted by ITV News, has been watched online by tens of thousands of people online and generated national headlines.