Politicians of all stripes are desperate for Rupert Murdoch's support when they are in power, but one former Australian leader is taking on the media baron in a bid to curb his vast empire of influence around the world.

Former Prime Minister Malcolm Turnbull has accused Murdoch's media empire of undermining democracy, and says a rigorous inquiry into Murdoch's News Corp is needed in the wake of a $1.6 billion defamation lawsuit against Fox News in the U.S.

The scathing criticism of the billionaire magnate follows the appointment of Turnbull as the head of a campaign that calls for a royal commission -- Australia's highest form of public inquiry -- into Murdoch's media dominance.

Murdoch's hold over politics and the media is most extensive in Australia, where News Corp owns close to 60% of the country's newspapers; pay TV company Foxtel and a conservative 24-hour channel, Sky News Australia, which has amassed more than 3 million subscribers on YouTube alone. Former U.S. President Barack Obama said the channel was fuelling the polarization of society at a sold-out address in Sydney on Tuesday.

"There is a public interest in asking the question: 'What are the consequences of this type of media operation?' because there is no doubt it is undermining our democracy," Turnbull said in an interview with Nikkei Asia. "There is an ability to really examine how News Corp is operating as a propaganda vehicle."

Pressure is mounting on Murdoch after the 91-year-old conceded that some of his Fox News commentators knowingly spread falsehoods about the 2020 U.S. presidential election. Dominion Voting Systems claims the TV channel amplified lies that their voting machines rigged the election against Donald Trump in favor of Joe Biden, who won the election. Debunked allegations of voter fraud, spread by Trump, helped spark a deadly attack on the U.S. Capitol on Jan. 6, 2021.

Turnbull said Fox News "was the single largest platform on which that lie was spread. If you are spreading falsehoods about the legitimacy of the government, you are creating the environment on which this sort of thing can happen."

"Jan. 6 was a catastrophe for the United States," he added. "It was a near coup that weakened America's standing all around the world, and was one of the most shocking events in American political history."

Turnbull believes Rupert Murdoch's bombshell deposition in the Dominion lawsuit case strengthens the case for a royal commission in his native Australia, which also has the power to subpoena documents and compel people to give evidence under oath.

"If Murdoch had nothing to hide, he would be saying, 'Bring it on,'" Turnbull said. "But [News Corp] knows if they were subjected to this type of rigorous inquiry ... they would find that very discomforting."

Turnbull will take over the campaign from another former prime minister, Kevin Rudd, who stepped down after he became Australia's next U.S. ambassador. Rudd has called Murdoch "an arrogant cancer" on Australian democracy and launched a petition calling for a royal commission into his empire in 2020, which attracted half a million signatures and triggered a parliamentary inquiry into media concentration in the country.

Turnbull will use his role as co-chair of the Australians for a Murdoch Royal Commission lobby group to urge advertisers to boycott the mogul's media outlets.

Australia is among the most concentrated media markets in the world. In 2016, a landmark study on media ownership conducted by academics across 30 countries found that only China and Egypt had a more concentrated newspaper market than Australia.

But News Corp has dismissed concerns about media concentration in Australia, claiming the industry is a "picture of diversity, not monopoly."

"Diversity is not just about ownership. It's about the diversity of views and diversity of sources. And, importantly, the incredible diversity in the way people now access news and information," News Corp Australia's executive chairman Michael Miller argued before a parliamentary inquiry in 2021.

"Australians are smart people who make up their own minds about what media they consume, who they back politically, and what they feel."

However, critics have blamed Murdoch for helping oust several Australian prime ministers whose agendas he disliked, including Turnbull, while his outlets have been accused of fuelling climate denialism and right-wing populism. So great is the media magnate's influence on Australia's political landscape that it has become a rite of passage for prime ministers to meet with him personally when they visit New York.

Despite often contributing to their downfall, Sally Young, a professor of political science at the University of Melbourne, said successive governments throughout Australia's history have often helped facilitate the Murdoch family's rise. "That's part of the political quid pro quo," Young said. "Favorable coverage, favorable policies."

But there are signs that Murdoch's vast influence over the Australian media and political landscape could be waning.

Last year, News Corp publications called for an end to the center-left Labor Party in Victoria and for the return of the Morrison Liberal government. However, the Victorian Labor Party was reelected for a third term, while Morrison was ousted in favor of Anthony Albanese. Last weekend, a Labor government was also elected in Australia's most populous state, New South Wales.

In 2020, News Corp shut down 100 print publications in Australia, leading to about 1,000 job losses. Longtime observers of the company believe it will also faces challenges once Rupert Murdoch is no longer at the helm. "If the throne gets passed [to his son, Lachlan Murdoch], I think there will be more mumblings of breakup of this News Corp empire," said Morningstar senior analyst Brian Han. "There is a great section of the market who believe the sum of its parts are greater than the whole."

News Corp Australia did not return requests for comment.

Turnbull, for his part, believes that while Murdoch's "influence over the electorate overall is less than it once was ... his influence over center-right and right-wing politics is much greater" both in Australia and the U.S.

The company, he said, has a "conscious desire" to pull center-right parties in a more conservative direction. "As a political party moves further to the right, it loses its centrist supporters and members, and therefore the influence of right-wing media becomes greater," Turnbull said. "The problem is [News Corp] is very influential with the [Liberal Party] base."

Turnbull, who has just launched a podcast examining whether Western democracies are in decline, said this could have a profound impact on future Australian elections which are a "two-horse race" between his center-right Liberals and the center-left Labor Party.

"[Australia's] electoral system is designed to bring politics to the center," said Turnbull, who is considered a moderate. "But when you have got a so-called news organization, that is more propaganda than news and is pushing an extreme line -- it brings real danger."