Gordon Brown struggled to maintain his political fightback yesterday as his allies accused the media magnate Rupert Murdoch of "sabotaging" the Labour conference.
Mr Brown's hopes that his conference speech on Tuesday would provide a springboard for a recovery were dashed a few hours later when The Sun newspaper announced it was withdrawing its support for Labour after 12 years and would endorse the Conservative Party at next year's general election.
Senior Labour figures circled the wagons to protect Mr Brown and declared war on the newspaper. But they were deeply frustrated that the controversy denied the Prime Minister the momentum he hoped for. Among Labour MPs, there was renewed speculation of a third attempt to oust Mr Brown when parliament returns from its summer break on 12 October.
Mr Brown's anger boiled over in a television interview with Sky News, also part of the Murdoch empire. After Adam Boulton, its political editor, suggested that Mr Brown's keynote speech had revealed no political philosophy, the Prime Minister told him: "You are sounding a bit like a political propagandist yourself."
He complained that Mr Boulton seemed to "obsess" about the Labour leadership issue, saying: "You have not given me the chance to talk about the economy." Insisting that he would not stand down before the election, he said: "I have got a job to do and that's the job I am going to do."
As the interview ended, a clearly livid Mr Brown started to storm off while the cameras were still rolling but forgot that he still had a microphone clipped on his jacket and had to sit down.
Labour's strategy to focus on policy differences with the Tories was blown off course by The Sun's deliberate and successful attempt to set the conference agenda.
Mr Brown said: "Obviously, you want newspapers to be for you. We would have liked everybody to be on our side, but the people decide [the election]. I've got an old-fashioned view that you look to newspapers for news not opinions."
Tony Woodley, joint general secretary of the Unite union, won the biggest cheer of the day when he ripped up a copy of yesterday's edition of The Sun at the podium. He told delegates: "We don't need an Australian-American coming to our country with a paper that has never supported any progressive policies from our party, including the minimum wage, telling us how politics should be run in this country."
Harriet Harman, Labour's deputy leader, told the conference: "I am speaking to you this morning about something The Sun knows absolutely nothing about: equality. The nearest their political analysis gets to women's rights is Page 3's News in Briefs. We are all angry about The Sun this morning but I say to you: don't get bitter, get better."
Pro-Labour adverts attacking the newspaper appeared on Google. Labour denied responsibility and the ads were later taken down.
Lord Mandelson, the Business Secretary, said: "I don't think the readers want The Sun to set on New Labour. The last thing that Sun readers want is to see their newspaper turned into a Tory fanzine."
Labour advisers insist the newspaper's long-expected conversion to the Tories would have less impact than its decision to come out for Labour in the run-up to the 1997 election. One strategist said: "Forty per cent of people don't read newspapers now, after the growth of the internet and 24-hour news channels."
A jubilant Mr Cameron welcomed the paper's support, but insisted he would not become complacent. "I think they have seen the Government is exhausted and out of ideas and they see a regenerated, refreshed Conservative Party ready to serve," he said.
Mr Brown faced further accusations of dithering over whether he would bow to Sky's campaign for a series of televised election debates with Mr Cameron and the Liberal Democrat leader, Nick Clegg. In a BBC interview, the Prime Minister admitted he had made up his mind but refused to say what his decision was. One Cabinet minister said: "I wish he would just get on with it and say yes."
Lord Mandelson said Labour's attitude to debates was "positive" and that it would now begin to consider how they might be organised.
Sky News had some better news for Mr Brown last night. A YouGov poll for the TV channel suggested that Labour has halved the Tories' lead during this week's conference. It shows the Tories on 37 per cent, Labour on 30 per cent, the Liberal Democrats on 21 per cent and other parties on 12 per cent.
The survey found 47 per cent of people believe Mr Brown should be replaced while 38 per cent think he should stay on. Some 64 per cent believe he is doing badly while 32 per cent are happy with his performance.
* Gordon Brown lost his cool in a live television interview yesterday as his leadership was called into question.
The Prime Minister accused Sky News's political editor, Adam Boulton, of appearing to "obsess" about his personality, and complained that he was not being allowed to discuss the economy. As Boulton repeatedly asked whether he would join a televised debate with David Cameron, Mr Brown protested: "You are sounding a bit like a propagandist."
The moment the interview ended, he tried to storm off without realising he was still attached to a microphone.