Politicians have been scrambling for a sensitive way to regulate the country's media after tabloid journalists were revealed to have intercepted celebrity voicemails, bribed police officers, trampled over people's privacy, and even hacked into computers in their hunt for scoops.
An inquiry ordered by Cameron and headed by Lord Justice Brian Leveson recommended the creation of a press watchdog body dominated by non-journalists and backed by government regulation, but negotiations between Cameron's Conservatives and others over how to implement those recommendations have stalled amid increasingly acrimonious debate.
In a hastily organized press conference, Cameron said the gap between politicians was unbridgeable and that he was pressing forward with his own plan for self-regulation formalized by government approval.
"I've chosen a practical solution over an unworkable solution," Cameron told journalists. "I have chosen a solution that protects press freedom over a solution that threatens press freedom."
Cameron plans to call a vote in Parliament on his self-regulation plan Monday, but it was not immediately clear whether his coalition partners, the Liberal Democrats, would give it the support it may need to pass.
Liberal Democrat leader Nick Clegg said he was "disappointed, and indeed surprised, that David Cameron has decided to walk away from cross-party talks."
Opposition Labour leader Ed Miliband said he would oppose Cameron's plan, and political watchers said the vote might be very close.
"It's a big gamble," said Paul Connew, a media commentator, former tabloid executive, and phone hacking victim who's closely followed the scandal and its aftermath. "As a believer in press freedom I hope he wins, but I'm not sure he will."
The debate between Cameron and his parliamentary colleagues centres on whether or not any future press watchdog should be set through an act of Parliament — through legislation — or through a Royal Charter, which is an executive act.
Proponents of legislation say that passing a law will put the watchdog on a firmer footing and give it more power to discipline rogue newspaper or resist pressure from media-friendly government ministers. Opponents of legislation believe, as Cameron put it Thursday, that passing a media law would bring Britain "over the Rubicon" and endanger the country's free press.
Those who back the Royal Charter — an act whose history dates back to medieval times — say it's a compromise solution that keeps the press free while still giving official blessing to a media watchdog. Opponents say the proposal gives both politicians and their media baron pals the ability to play with the system.
Labour Lawmaker Chris Bryant, whose phone was hacked by Rupert Murdoch's now-defunct News of the World tabloid, told BBC television that "we need a body that is completely independent both of politicians and of the newspapers and it has to have statutory underpinning so you can't just have some government minister coming along and changing it at will."
Former Formula One boss Max Mosley, who sued the News of the World for invasion of privacy over the paper's false claims he had taken part in a Nazi-themed orgy, said legislation was required for an enduring solution.
Mosley told the BBC that Cameron — who drew two of his closest advisors from the News of the World before they were arrested — was bending over backwards to satisfy his allies in the media.
"He's doing everything he can to satisfy the press," Mosley said. "But that doesn't satisfy the rest of us."