Fox personalities have worked to mainstream the racist conspiracy theory that non-white immigrants threaten to “replace” white American populations. Hosts Tucker Carlson and Laura Ingraham, whose shows regularly revolve around the purported dangers immigration poses to the cultural fabric, have been particularly taken with that argument, and they are not subtle in its promotion.

“Your views on immigration will have zero impact and zero influence on a House dominated by Democrats who want to replace you, the American voters, with newly amnestied citizens and an ever increasing number of chain migrants,” Ingraham told her audience shortly before the 2018 midterms.

“It's not a conspiracy theory, it's happening in public,” Carlson has argued. “[Democrats’] political success does not depend on good policies, but on demographic replacement, and they'll do anything to make sure it happens.”

Carlson is particularly beloved by white nationalists, who believe he “is making the white nationalist talking points better than they have,” as the son of the founder of hate website Stormfront put it in March. The Fox host regularly warns of the dire consequences immigration poses to the country. He has said that immigration “is absolutely destroying America” and will “change this country completely and forever”; argued that “we’re being invaded” by migrants in a way that could trigger a national “collapse”; and claimed that “we are importing people from places whose values are simply antithetical to ours,” putting the nation’s ability to “survive” at risk.

The description of migration across the southern border as an “invasion” has become so common on Fox that it hardly warrants mention at this point. That is simply the language the network’s personalities -- even its purported “straight news” anchors -- use to describe migrants, often as Fox airs B-roll of columns of Hispanic men marching north.

Though the alleged shooter's ideas seem to echo what Fox airs every night, the language in his manifesto differs from the network's in one small way: Its references to race are explicit, while Fox’s commentators often talk around that. But this is largely a distinction between text and subtext. The invaders who Fox hosts keeps warning might destroy the country through demographic replacement are Black and brown, as both the hosts and their audience know.

The network appears deeply committed to airing talking points previously confined to the fever swamps. Their use has continued even as white supremacists enact mass murders, and Fox has defended Carlson and Ingraham from advertiser boycotts triggered by their bigoted language on immigration.

Fox’s use of this rhetoric of demographic replacement and migrant invasion has not occurred in a vacuum. It has been mirrored by Republican politicians, including President Donald Trump, who similarly deploy those racist tropes. That's no coincidence -- both Fox and the GOP depend on riling people up with racist appeals for their success. Their behavior won't change unless their incentives change.