Ilustration: John Spooner More recently, Kerry Packer ditched Paul Keating in 1995 to back John Howard instead. In 2007, the Murdoch press gave Kevin Rudd a lukewarm boost, only to turn on him viciously later. Politicians rarely please media moguls for long. A Labor frontbencher who experienced the shift from Murdoch's enthusiastic support in 1972 to his wrath in 1975, told journalist Max Walsh at the time that media barons "never show you any gratitude; they regard it as a right and not a favour and they are always there with their hands out for more". Because Abbott was such a default leader within his own party – winning the internal leadership battle by one vote and never popular with voters – the Murdoch press's support for him was gratefully accepted. That support was so ostentatious that it only increased Abbott's debt.

Abbott was never likely to be able to deliver to Murdoch's satisfaction. This is especially so because the winds of change buffeting newspapers and working against the success of Foxtel in an era of internet streaming mean Abbott cannot solve all of Murdoch's business problems through national media policies. Abbott did reduce funding to the ABC, limiting what Murdoch views as a privileged competitor. And he did hobble the NBN, reducing the capacity for internet-streaming rivals. But there is still so much left to do and Abbott has been unable to deal well with what the Murdoch press repetitively calls a "feral Senate". Whatever the source of Murdoch's dissatisfaction – whether it is about thwarted policy outcomes or just growing acceptance that Abbott would never be a popular, effective leader at the time – Murdoch has now very publicly sealed Abbott's fate. Last week, Murdoch put Abbott to a cruel public test. It has been apparent for months that Abbott's chief of staff, Peta Credlin, has done something to displease Murdoch/News Corp. Her name started coming up in unglowing terms months ago. But, last week, Murdoch applied the blowtorch by tweeting a public demand that Abbott sack Credlin. This is a staff member Abbott is said to be "intensely loyal" and "close" to. Murdoch put Abbott in a no-win situation. If Abbott sacked Credlin, he would look like Murdoch's poodle. If he didn't, the Murdoch press would use it as a justification for pulling support.

Did one of News Corp's columnists, Miranda Devine, reveal the problem when she said at the weekend that Credlin was not returning the phone calls of "important people". Who could this be? News Corp editors? Murdoch himself? It is unprecedented to use a staff member in a public tug-of-war, so there is obviously a story there. If it is not known now, it will come out eventually. Murdoch has a long reputation for using his media outlets as blunt tools of political influence, but he also had a reputation for backing winners. That record is now waning, most recently by backing losers in Victoria and Queensland. As Murdoch has become more ideological, he has become less politically pragmatic and his outlets have followed suit. News Corp has been doing precisely what it is now criticising Abbott for - being out of touch and making poor choices. It is increasingly partisan and simplistic while voters become increasingly less partisan and more sophisticated. It has alienated opponents who then form governments, making it increasingly difficult to get its own agenda through to safeguard its businesses in difficult times. Murdoch reportedly approved of Abbott's unpopular parental leave policy. What is different about this relationship break-up from all of the ones before is that this has been so public - a break-up message via Twitter from an octogenarian is so very 21st century.

Of course, there were private meetings and phone calls we don't know about, but, the day after Abbott won, a headline in Murdoch's Sunday Mail was: "Now he has to repay the faith". Chillingly, it looked like a public message demanding payback. There were other public moments, such as Abbott photographed kneeling at Murdoch's side at a dinner and Murdoch's supportive tweets, which meant his journalists no longer had to wait for his internal memos. At the end of 2014, News Corp delivered Abbott a public "warning" to change course. Now, the message seems to be "you're done". We have a long history in this country of powerful media owners influencing politics, but it is usually more subtle, nuanced and behind-the-scenes than this. At least a public bromance and break-up creates public awareness and encourages critique. Even the posts under News Corp's own articles online suggest readers know what is going on. So, who will News Corp turn to as they ponder life after Abbott? Scott Morrison? Julie Bishop? If Malcolm Turnbull does become leader, things are about to get more interesting. Turnbull worked for Kerry Packer, has known the Murdochs for decades and ran his own internet company. In the Australian media industry, he knows where the bodies are buried. He also understands the psychology of media magnates and does not seem to fear their tantrums. Turnbull's reputedly bullet-proof ego might serve him well in dealing with media owners.

Whoever is in charge certainly needs all of their nerve, because the only thing more disturbing than our Prime Minister awarding an Australian knighthood to a British prince, is an American media mogul directing our Prime Minister what to do. Sally Young is a regular Age columnist and an Australian Research Council Future Fellow studying press power in Australia. She is an associate professor of political science at the University of Melbourne.