On Wednesday night, the Fox News presenter Tucker Carlson once again talked about the alleged plight of white South African farmers on his Fox News program.

On Twitter, Donald Trump indicated that he had been watching. The president’s tweet called for further study, but treated the “large scale killing of farmers” as a settled fact, when reporting indicates that against the background of a generally high murder rate in South Africa, there is no evidence of white farmers being specifically targeted.

But Trump’s tweet came at the end of a long process whereby the far-right idea of “white genocide” in South Africa had been mainstreamed, working its way from far-right websites and forums, into the rightward edge of mainstream media, and then into policy proposals. News Corp outlets have played an outsized role in that process.

The conspiracy theory of “white genocide” has been a staple of the racist far right for decades. It has taken many forms, but all of them imagine that there is a plot to either replace, remove or simply liquidate white populations.

South Africa and Zimbabwe in particular have exerted a fascination on the racist far right because in the mind of white nationalists, they show what happens to a white minority after they lose control of countries they once ruled.

The Charleston shooter Dylann Roof was obsessed, like many other white supremacists, with “Rhodesia”, as Zimbabwe was known under white minority rule. As the Christian Science Monitor reported in the wake of his massacre, the fates of the two countries are “held up as proof of the racial inferiority of blacks; and the diminished stature of whites is presented as an ongoing genocide that must be fought”.

Tucker Carlson poses for photos in a Fox News studio. Photograph: Richard Drew/AP

More recent advocacy for South Africans on the racist far right has been brought about by the government’s moves on land reform, and some skilled and relentless entrepreneurship from the South African far right on the issue.

A key figure in this enterprise is Simon Roche, a senior member of the millennialist, white nationalist and survivalist group the Suidlanders, who in their own words exist to “prepare a Protestant Christian South African Minority for a coming violent revolution”, or race war.

In 2017, Roche traveled extensively in the United States and beyond, promoting the idea that whites in South Africa were under attack, and at risk of ethnic cleansing.

Roche appeared not only at far-right conferences like “American Renaissance”, and on a whole range of “alt-right” podcasts, but also in interviews with “alt-light” figures with large, crossover audiences, such as Stefan Molyneux and Mike Cernovich.

Through late 2017 and early 2018, the idea of South African white genocide was picked up by ostensibly more mainstream figures.

Ann Coulter promoted the idea that white farmers were “the only real refugees” in a retweet of white nationalist Tara McCarthy. Tucker Carlson’s claim in March that South Africa was “falling apart” due to the process of land reform was dutifully reposted at reddit’s Trumpist hub, The Donald. Katie Hopkins memorably visited South Africa in preparation for a documentary on the subject. And Willem Petzer, described by the independent media organisation Unicorn Riot as a “racist internet pundit”, has been a guest of Proud Boys founder Gavin McInnes on his podcast, and hosted McInnes in return on his YouTube channel.

Meanwhile, petitions appeared appealing to Trump to accord special immigration status to white farmers, some attracting thousands of signatures.

In March, the alleged plight of the farmers became the subject of a campaign by News Corp tabloids in Australia.

In a preview of Trump’s response, the News Corp intervention led the then home affairs minister, Peter Dutton, to float a short-lived proposal to give preferential immigration treatment to farmers. The move was praised by white nationalists on forums like Stormfront, and cited by rightwingers of all kinds as evidence of the issue’s importance. Roche and the Suidlanders claimed credit for the development. (As at this writing, Peter Dutton is involved in an internecine struggle for Australia’s prime ministership.)

Rallies in several Australian cities drew hundreds of people to demonstrate on behalf of South African farmers, and attracted politicians, including some from the governing Liberal party. In the United States, politicians reportedly met with members of other Afrikaner groups on the issue.

Since then, Lauren Southern, who has become one of the far-right’s breakout e-celebrities, has completed and heavily promoted a documentary on the issue, entitled Farmlands. That film was a centerpiece of her recent tour of Australia with Stefan Molyneux. Southern, and her advocacy on the issue, received extensive promotion in News Corp properties.

Last Monday, another Southern appearance indicated how important the issue was becoming to the big dogs in US rightwing media.

Talk radio host Michael Savage devoted an entire show to the issue, and presented Southern and Katie Hopkins to his 11 million listeners to speak about their own trips to South Africa.

Savage – regularly described as one of the most influential talk radio hosts in the country – repeatedly described the situation as “genocide”. When Southern was asked how people could support the farmers, she mentioned the Suidlanders, and urged listeners to contact politicians about the issue. Savage also promoted his own petition to Trump on behalf of the farmers.

On Twitter, he was incensed at Carlson receiving credit for the president’s moves on the issue.

But, as in Australia, the crucial step in creating a policy proposal issue appears to have been advocacy by a News Corp outlet, in this case Tucker Carlson’s program. Indeed, News Corp now appears to be a crucial conduit for far-right ideas to reach governments.

This development has been celebrated overnight by the racist far right, but so too has the whole process by which “white genocide” has become a matter of broader public debate.

Earlier this year, an anonymous podcaster on the white genocide-focused “White Rabbit Radio” said: “This was the province of Stormfront five, 10 years ago, white genocide in South Africa. Now it is mainstream.”