The parents of murdered schoolgirl Milly Dowler have criticised the government's approach to reforming the press.
Bob and Sally Dowler said they were "very disappointed" that Lord Justice Leveson's recommendations may not all be implemented by Parliament in a crunch vote on Monday.
Their intervention, believed to be the first time they have spoken out on the issue since the Leveson Report was published in November, ramps up the pressure on David Cameron, who is facing a battle to get his proposals through the Commons.
Labour and the Liberal Democrats have teamed up to oppose the Prime Minister's plans. They want a new press regulator to be supported by statute, which is opposed by the Tories over fears for press freedom.
Cameron has previously told phone-hacking victims that Leveson's recommendations would be implemented unless they were "bonkers".
Thirteen-year-old Milly Dowler's mobile phone was hacked during her disappearance by a private detective working for the now defunct News of the World.
In a statement released by their solicitor, Mark Lewis, Mr and Mrs Dowler said: "Given the considerable investment of time and money in the Leveson Inquiry, we are very disappointed to learn that Lord Justice Leveson’s proposals may not now be taken forward if the politicians choose to ignore the recommendations of LJ Leveson that were aimed at preventing the sort of abuses that we and so many others suffered."
Lewis said it was "plain for all to see how self regulation failed abysmally."
He added: "Politicians should not peddle the lie that implementing Leveson would restrict press freedom.
"We do not have press freedom - certain parts of the press have abused their privilege without taking responsibility.
"This is the opportunity to bring back integrity to the journalistic profession and challenge the cowardice of politicians who are too scared to stand up to the vested interests of huge media groups.
"Failure to implement Leveson is not only failing the Prime Minister's 'Dowler test', but failing the electorate as a whole."