The father of missing Madeleine McCann said David Cameron could squander a "historic opportunity" for press reform following the end of cross-party talks into regulation.
Gerry McCann said the prime minister was faced with choice between either supporting newspaper barons or the victims of press intrusion, saying: "We want our politicians to protect us, to stand up for the ordinary victims instead of siding with the wealthy and powerful."
His comments come after Cameron pulled the plug on efforts to reach a cross-party consensus, announcing he will bring the matter to a head by forcing a vote in the House of Commons on Monday.
"On Monday, it comes down to a binary choice: the newspaper barons or the people they abused in search of profit. Leveson or more of the same. It is as simple as that."
In the wake of the dramatic end to cross-party talks, Mr McCann told the Press Association: "What concerns me greatly is that an historic opportunity for press reform may be about to be squandered.
"Lord Justice Leveson's proposals were measured and modest.
"They didn't go far enough in my view. But I and other victims of gross press misconduct were prepared to regard them as the minimum acceptable compromise.
"We gave evidence to the inquiry so that some lasting good might come out of a horrendous experience."
The dramatic move prompted campaigners to accuse Mr Cameron of a "shameless betrayal of victims of press abuse".
Mr McCann and his wife Kate, whose daughter went missing when the family was on holiday in Portugal in 2007, gave moving evidence during the Leveson Inquiry about their experience at the hands of the media, where Mr McCann described how his wife felt "mentally raped" by the News of the World's publication of her intensely-personal diary.
The coverage of the disappearance of Madeleine was given by Lord Justice Leveson as an example of how stories ran "totally out of control".
When the Leveson report was published in November, Mr McCann said if its recommendations on press regulation were not implemented, giving evidence to the inquiry would have been "almost useless".
- Police 'Hunt Six British Cleaners Working In Portugal When Madeleine McCann Disappeared'
- Labour And Liberal Democrats Criticise David Cameron For Ending Talks
- Stage Set For Crunch Talks On Monday
He urged politicians to "do the right thing" and accept in full the suggestions for a new regulatory system, while his wife said she hoped it would mark the start of a new era for the press, urging Mr Cameron to "embrace the report and act swiftly".
A year before, Kate McCann had told the inquiry she felt like "climbing into a hole and not coming out" when the News of the World printed her journal, which she began after Madeleine disappeared.
"I felt totally violated. I had written these words at the most desperate time of my life, and it was my only way of communicating with Madeleine," she told the inquiry.
The diary, which was so private Mrs McCann did not even show it to her husband, was published in the News of the World on Sunday September 14 2008. The now-defunct newspaper later apologised.
"There was absolutely no respect shown for me as a grieving mother or a human being or to my daughter," Mrs McCann said.
"It made me feel very vulnerable and small, and I just couldn't believe it."
Lord Justice Leveson's report described how the McCanns, although originally given favourable coverage in the media, were treated like a commodity, in a similar way to Milly Dowler's parents.
"The McCanns were also treated as if they were a commodity in which the public, and by extension the press, had an interest or stake that effectively trumped their individual rights to privacy, dignity or basic respect," it said.
"Also like the Dowlers, the McCanns were the victims of grossly intrusive reporting, prying photographers and an ongoing 'media scrum' which paid little or no regard to their personal space, their own personal distress and, in particular, the interests of Madeleine's younger siblings."
It added: "If ever there were an example of a story which ran totally out of control, this is one.
"The appetite for 'news' became insatiable, and once the original story had run its course the desire to find new leads and 'angles' began to take over, with their corollary tendencies of sensationalism and scandal.
"Not merely was the rigorous search for the truth the first principle to be sacrificed but also was any respect for the dignity, privacy and wellbeing of the McCanns."