On Monday morning, President Trump finally got around to reciting a few appropriate sentences about the lethal violence that white supremacists had unleashed over the weekend at a rally in Charlottesville, Virginia. “Racism is evil,” the President announced. The guilty will be prosecuted. Heather Heyer, who was struck when a car drove into a crowd of counter-demonstrators, did not deserve to die.

But the public will not soon forget Trump’s first utterance after the events of Saturday. The violence, he said, had come from “many sides.” In fact, the violence had been instigated not by many sides but by one: the extremist right, whose followers apparently include the twenty-year-old man charged with killing Heyer in an attack that injured nineteen others. A number of prominent Republicans spoke of the events in less equivocal terms; Senator Ted Cruz, of Texas, was among those who called the killing an act “of domestic terrorism.”

As the nation waited through the weekend for a further response from Trump, he found time, first, to attack Kenneth C. Frazier, the chief executive of Merck. Frazier, who is African-American, had just resigned from the President’s American Manufacturing Council, because, he said in a statement, “America’s leaders must honor our fundamental values by clearly rejecting expressions of hatred, bigotry and group supremacy.” In response, Trump tweeted that Frazier would now “have more time to LOWER RIPOFF DRUG PRICES!” (By the end of the day, Kevin Plank and Brian Krzanich, the C.E.O.s of Under Armour and Intel, respectively, had also quit the council.)

Trump’s emotions are unusually transparent, but, as he spoke on Monday morning, from the White House, he sounded like a hostage forced to read a message in a ransom video. This is hardly the first time that he has been hesitant to distance himself from right-wing extremists. During the campaign, for example, when David Duke, the former Grand Wizard of the Ku Klux Klan, endorsed him, he did not immediately repudiate Duke’s support. Eventually, following a barrage of criticism similar to the one that he received this past weekend, Trump issued a mild disavowal.

The origins of Trump’s support on the far right are examined in Joshua Green’s indispensable new book, “Devil’s Bargain: Steve Bannon, Donald Trump, and the Storming of the Presidency,” which illustrates how a failed business venture led to an insight that undergirded Trump’s Presidential bid. In 2005, Green writes, Bannon moved from Hollywood, where he was a modestly successful producer, to Hong Kong, where he proposed to capitalize on the popularity of the online video game World of Warcraft, which had ten million subscribers. In the game, players competed for virtual weapons, armor, and gold. Bannon hoped to profit from an arrangement that allowed players to pay real money to attain these virtual trophies—an idea that quickly collapsed.

In the process, however, Bannon discovered a universe of young men who spent their days in imaginary worlds behind their computer screens. They were literate, at least moderately well off, and manifestly alienated from the world around them. As Green recounts, Bannon saw that they represented a group that could be turned into a movement. “These guys, these rootless white males, had monster power,” Bannon told Green. Then, shortly after he returned from Hong Kong, Bannon took over the late Andrew Breitbart’s right-wing Web site. As Green writes, Bannon “envisioned a great fusion between the masses of alienated gamers, so powerful in the online world, and the right wing outsiders drawn to Breitbart by its radical politics and fuck-you attitude.” Breitbart News appealed to certain disaffected young men by building on their resentments—of African-Americans, of women, of Jews—and became, as Bannon proudly noted, the “platform of the alt-right.” More to the point, Breitbart also became an enthusiastic supporter of the Trump campaign and, later, the Trump Presidency.

Just as it was easy for Bannon to draw a line from the young males of the online-game world to the young males of the alt-right, it’s similarly straightforward to draw a line from the alt-right to the protesters in Charlottesville. Such people do not comprise the bulk of the President’s base, but they are a dedicated part of it, and he has shown great solicitude for their views. As if to demonstrate that fact, on Sunday, Trump told Fox News that he might pardon Joe Arpaio, the former sheriff of Maricopa County, Arizona, who was recently convicted of criminal contempt, and who has long been suspected of federal civil-rights violations.

Trump has built his Presidency by catering to the interests and prejudices of his core base, rather than by trying to expand his field of supporters. His initial reaction to the tragedy in Charlottesville, not his latter-day semi-recantation, is a case in point. It remains to be seen whether this strategy will bring him success, or reëlection, but it is the path he has chosen.