Alarmist? Sure. But Mr. Yang’s doomsday prophecy echoes the concerns of a growing number of labor economists and tech experts who are worried about the coming economic consequences of automation. A 2017 report by McKinsey & Company, the consulting firm, concluded that by 2030 — three presidential terms from now — as many as one-third of American jobs may disappear because of automation. (Other studies have given cheerier forecasts, predicting that new jobs will replace most of the lost ones.)

Perhaps it was inevitable that a tech-skeptic candidate would try to seize the moment. Scrutiny of tech companies like Facebook and Google has increased in recent years, and worries about monopolistic behavior, malicious exploitation of social media and the addictive effects of smartphones have made a once-bulletproof industry politically vulnerable. Even industry insiders have begun to join the backlash.

To fend off the coming robots, Mr. Yang is pushing what he calls a “Freedom Dividend,” a monthly check for $1,000 that would be sent to every American from age 18 to 64, regardless of income or employment status. These payments, he says, would bring everyone in America up to approximately the poverty line, even if they were directly hit by automation. Medicare and Medicaid would be unaffected under Mr. Yang’s plan, but people receiving government benefits such as the Supplemental Nutrition Assistance Program could choose to continue receiving those benefits, or take the $1,000 monthly payments instead.

The Freedom Dividend isn’t a new idea. It’s a rebranding of universal basic income, a policy that has been popular in academic and think-tank circles for decades, was favored by the Rev. Dr. Martin Luther King Jr. and the economist Milton Friedman, and has more recently caught the eye of Silicon Valley technologists. Elon Musk, Mark Zuckerberg and the venture capitalist Marc Andreessen have all expressed support for the idea of a universal basic income. Y Combinator, the influential start-up incubator, is running a basic income experiment with 3,000 participants in two states.

Despite its popularity among left-leaning academics and executives, universal basic income is still a leaderless movement that has yet to break into mainstream politics. Mr. Yang thinks he can sell the idea in Washington by framing it as a pro-business policy.