This week, Donald Trump’s campaign took a new and even darker turn. As multiple women accused the Republican Presidential nominee of sexual harassment and sexual assault, Trump gave speeches on Thursday and Friday that had two themes: he denied all the charges against him, most notably by arguing that his accusers were not attractive enough for him to assault, and he claimed that the accusations are part of a global conspiracy against him, involving the Clintons, the news media, and international banks.

“Hillary Clinton meets in secret with international banks to plot the destruction of U.S. sovereignty in order to enrich these global financial powers, her special-interest friends, and her donors,” Trump told a raucous crowd of supporters in West Palm Beach, Florida, on Thursday. On Friday, in Greensboro, North Carolina, he added that Times reporters were “corporate lobbyists for Carlos Slim,” the Mexican billionaire who is the newspaper’s largest single investor.

Trump has long been a conspiracy theorist. He gained a prominent role in American politics in 2011 by questioning Barack Obama’s birthplace. In 2012, he claimed that “the concept of global warming was created by and for the Chinese in order to make U.S. manufacturing non-competitive.” During this election, he has alleged that Obama founded ISIS, that Ted Cruz’s father, Rafael Cruz, was involved in John F. Kennedy’s assassination, that the Department of Labor fakes its unemployment numbers, and that the Justice Department colluded with Hillary Clinton to let her off the hook in its investigation of her use of a private e-mail server while she was the Secretary of State.

It’s no surprise, then, that Trump has been advised for decades by Roger Stone, a prominent political strategist and conspiracy theorist who believes that Lyndon B. Johnson had Kennedy killed (Stone is silent on Rafael Cruz’s role) and that George H. W. Bush may have tried to kill Ronald Reagan. It’s also not shocking that Trump has been a regular guest on the radio show of Alex Jones, who, among other interesting things, believes that Americans are in danger of being controlled by “clockwork elves.”

But it took someone a little smarter—and more cynical—than Trump, Stone, or Jones to distill Trump’s platform of protectionism, closed borders, and white identity politics into one message about a global conspiracy. The man behind this new message is Steve Bannon, who became the C.E.O. of the Trump campaign in August. Bannon is on leave from Breitbart, the right-wing news site where he served as executive chairman, and where he honed a view of international politics that Trump now parrots.

Bannon, who is sixty-two, is new to right-wing rabble-rousing, compared to someone like Stone. Bannon was raised in a blue-collar Democratic family around Norfolk and Richmond, Virginia. He served in the Navy, went to Harvard Business School, and became wealthy as a mergers-and-acquisition deal-maker for Goldman Sachs, in the nineteen-eighties. He made a fortune by buying a share of the royalties for “Seinfeld” back in 1993, and receives them to this day.

Bannon met Andrew Breitbart, the founder of the news Web site, when Bannon was financing conservative documentaries in Los Angeles in the aughts. Breitbart, who previously worked with the Drudge Report, started Breitbart, in 2005, as a conservative news aggregator, much like his former employer. In the fall of 2009, Bannon and Breitbart worked together on a business plan to launch a more ambitious version of the site, and Bannon joined its board in 2011, once the financing deal closed. When Andrew Breitbart died, in 2012, Bannon became executive chairman and took over the site. Back then Breitbart was a pugnacious but still recognizably conservative site, but, with Bannon in charge, its politics started to change.

Bannon embraced the growing populist movement in America, including the “alt-right,” a new term for white nationalists, who care little about traditional conservative economic ideas and instead stress the need to preserve America’s European heritage and keep out non-whites and non-Christians. Under Bannon, Breitbart promoted similar movements in Europe, including the United Kingdom Independence Party, the National Front in France, Alternative for Germany, and the Freedom Party in the Netherlands. Bannon likes to say that his goal is “to build a global, center-right, populist, anti-establishment news site.” After the election is over, Breitbart, which has offices in London and Rome, plans to open up new bureaus in France and Germany.

This ambition extends to supporting the election of right-wing candidates. In 2013, Bannon encouraged Senator Jeff Sessions, of Alabama, who led the opposition to immigration reform, to run for President, but Sessions declined to enter the race. Bannon went on to attend early candidate forums, where he noticed that, while most Republicans stuck to the Party’s small-government message, Trump was hitting the protectionist themes that proved popular at Breitbart and on the European right. Back then, when he tried to get one national newspaper reporter to interview Trump, he was told, “My editor would think I’d lost my fucking mind. Donald Trump’s a clown.”

In early 2015, Breitbart tilted toward Cruz, but after Trump entered the race that summer, with a sharper anti-immigrant message, Breitbart evolved into an unofficial arm of the Trump campaign. “Donald Trump: Candidate for Our Age” and “20 Reasons Why It Should Be Donald Trump in 2016” were typical headlines. When Trump fired his campaign director, Paul Manafort, in mid-August, he made Kellyanne Conway, a Republican pollster, his new campaign manager, and named Bannon his campaign C.E.O. (I profiled Conway for the magazine last week.)

Bannon has a few unusual views that are important to understanding Trump’s speeches this week. He believes that the white working class is still the key to the election, because the Clintons have never been able to win without this demographic. While Bill Clinton won two Presidential elections with the support of white working-class voters, this view is wildly at odds with recent changes in the electorate, which have made the Democrats more reliant on minority voters and college-educated whites. Other advisers, including Conway, tried to steer Trump toward appealing to these groups, but Trump has clearly turned away from them and toward Bannon.

Bannon’s view of the media is similarly narrow. He sees the dominant conservative media players as the establishment, not as allies. He views Fox News as highly unreliable on the nationalist cause, and was not unhappy when Roger Ailes, Fox News’s former C.E.O., was forced to resign over multiple sexual-harassment allegations. He despises Rupert Murdoch—the chairman and C.E.O. of the News Corporation, and now the acting C.E.O. of Fox News, one of its subsidiaries—as a pro-open-borders globalist. When Bannon ran Breitbart, he didn’t want his reporters appearing on Fox, because he believed the cable news channel had made smaller conservative news outlets subservient to it. After the first Republican primary debate, in August, 2015, when Trump became engaged in a highly personal fight with Megyn Kelly, Fox’s biggest star, Breitbart also gleefully attacked Kelly.

Bannon has never been a campaign strategist. He is a right-wing new-media entrepreneur who is building a political and news infrastructure that mimics Europe’s nationalists. After Trump’s speech on Thursday, when he linked Clinton to “international banks” and “global financial powers,” Jonathan Greenblatt, the head of the Anti-Defamation League, issued a statement that Trump “should avoid rhetoric and tropes that have historically been used against Jews and still reverberate today.”