I can reveal that Trinity Mirror, publisher of the Mirror titles, has pulled out of talks to create a joint advertising initiative across Britain's national newspaper industry.
Extensive discussions between leading Fleet Street executives over the past several months have been aimed at combating the structural decline of the market, as annual display advertising diminishes by around 20% and circulations continue their downward trajectory.
The talks have been hampered by personality clashes, the competing priorities of different groups, and the sheer novelty of companies whose commercial operations had hitherto been aggressive rivals, trying instead to co-operate for mutual advantage.
Project Rio will continue, with News UK, Telegraph Media Group, and the owner of The Guardian still trying to collaborate.
DMGT, the publisher of the Daily Mail, pulled out of Project Rio in January, saying it had "stepped back" to pursue "broader commercial priorities" in 2017. These include the monetisation of Mail Online, which has expanded quickly into America and is a priority of Paul Zwillenberg, chief executive of DMGT.
On 10 January I revealed that Trinity was in talks with Northern & Shell, the newspaper group run by Richard Desmond, and David Montgomery, the former newspaper executive and investor, about back-office consolidations.
My recent conversations with very senior sources in the industry make clear that the failure to progress this work on consolidation, which could potentially reap huge savings, is a source of immense frustration to the parties involved.
For Trinity, focusing on that consolidation is a higher priority than Project Rio.
But with the flight of advertising from print to digital accelerating, and Facebook and Google tightening their grip on that money, newspapers are struggling to make enough money from their websites to offset the loss of money from print, due to structural decline.
Even after the closure of the print Independent (of which I was editor) last year, Britain's newspaper sector is very full - and arguably over-supplied - for a country with our population size.
As this blog has repeatedly argued, bloated sectors facing structural decline are bound to consolidate. For Fleet Street, it's a question not of when, but how.
I've been sent a statement on behalf of Telegraph Media Group, Guardian Media Group and News UK.
It says: "Telegraph Media Group, Guardian Media Group and News UK today confirmed their continued commitment to working together to significantly improve the commercial value and perception of the news brands in the UK.
"Trinity Mirror have confirmed that they will step aside from involvement in the next phase of the project, whilst wishing it well and reserving an option to rejoin at a later stage.
"The three partners are working with market-leading consultancies on building the right approach to ensure that the industry continues to evolve to service key client and agency needs."