Labour MPs are demanding answers from the party HQ over the coming weekend's political and musical concert dubbed JezFest.
The one-day Labour Live event will take place in Tottenham, north London, on 16 June. Musical acts include The Magic Numbers and Reverend and the Makers, alongside speeches by John McDonnell, Kate Osamor and activist Owen Jones as well as party leader Jeremy Corbyn.
But there are growing concerns that organisers are struggling to fill the 20,000-capacity White Hart Lane Recreation Centre. As a result the Labour party has started giving out free tickets to regional party offices, as well as putting on free buses to bring people into the capital, while Unite the union has bought up 1,000 tickets.
Despite this, attendance figures are being estimated at around 3,000 people, and fears are growing that the concert will be a "big loss-maker".
One Labour MP told City A.M. it was "embarrassing".
"We are providing all these buses at enormous cost and giving away all these tickets to avoid the appearance of an empty event," he said. "They put far to much stock in Jeremy's ability to draw a crowd and not enough in getting decent acts... had they booked Stormzy the tickets would have sold themselves.
The chaos is prompting MPs to demand answers over the cost to the party, but Labour's general secretary Jennie Formby last week said "they are sensitive, and she is not prepared to share them", an MP said.
"Labour HQ and Jeremy’s office have bought into their own hype," the MP added. "You can't even give these tickets away."
"The danger is that it will be brushed under the carpet. There needs to be an internal post mortem about how this happened, what went wrong, why we didn't see it coming and why the Labour party was exposed to such significant financial and political risk."
Another MP said if money were lost on the tickets "we would have to have an investigation" into what went wrong.
He went on to complain that its London focus meant it had alienated many Labour supporters.
"It should have been held in the North," he said. "There aren't any people coming from my area."
A Labour party spokeswoman declined to comment on the cost of the event or other specifics.
However, she issued a statement saying: “Labour Live is a festival of music, art and politics, bringing people together from all walks of life.
“This is one of the ways we’re continuing to open up politics to a wider audience and spread Labour’s message about how we can build a society that works for the many, not the few.”