Most Democratic voters say that they favor a wealth tax, but a California ballot initiative has plenty of liberal opponents.

It wasn’t so long ago that Silicon Valley was, to use its own language, a major node in the Democratic Party’s network. The Valley’s origins were in developing electronic equipment for corporations and the military, but with the dawning of the age of the personal computer, half a century ago, it began to adopt the vernacular of anti-organizational hippie culture. It seemed entirely appropriate that a canonical text of the early internet, “A Declaration of the Independence of Cyberspace,” was written by a Grateful Dead lyricist, John Perry Barlow. For a time, the PC, the internet, and social-media networks all seemed to be vehicles for personal liberation and grassroots political empowerment.

The first two Democratic Presidents during the Valley’s apotheosis, Bill Clinton and Barack Obama, presented themselves as technology-friendly futurists, and the Valley supported their campaigns and helped staff their Administrations.

People often talk about our times as a second Gilded Age. During the first—the term was coined by Mark Twain and Charles Dudley Warner to describe the rise of industrial fortunes after the Civil War—the country had, by modern standards, a very small national government and very low taxes. In 1879, a social reformer named Henry George published a book called “Progress and Poverty,” which argued for remedying the era’s excesses by replacing all existing taxes with a single tax on land, which was a main form of wealth at the time.

The book sold three million copies in the United States during the eighteen-eighties and nineties—more than any other book except the Bible—and double that worldwide. In Britain, “Progress and Poverty” outsold Shakespeare. In 1886, George ran for mayor of New York City and got thirty per cent of the vote, finishing ahead of a young Theodore Roosevelt.

Dave Regan, the president of Service Employees International Union-United Healthcare Workers West, doesn’t come across as a member of what Thomas Piketty calls the Brahmin left. A bluff, tough sixty-year-old with a full head of white hair, he is the son of a homicide cop from Buffalo and spent the early stages of his career presiding over a Rust Belt local. In 2009, the national head of the S.E.I.U., Andy Stern, sent Regan to California.

In late September, polls showed that a slight majority of decided voters were in favor of Proposition 40. But the initiative has far less support than you’d expect from Democratic elected officials. Though the California Democratic Party has endorsed it, only three members of the California congressional delegation and ten members of the state legislature have done the same. California’s two U.S. senators have declined to support it; Xavier Becerra, Newsom’s likely successor, is opposed.

Katie Porter, a former member of Congress who ran unsuccessfully for governor this year, is another opponent of the initiative. “It pours money into the for-profit health-care industry, which is already ripping people off,” she told me. “We have people with two hundred million, three hundred million, eight hundred million in assets, and it says to them, ‘You don’t need to give anything.’ ” Porter said, of Democrats thinking about running for President in 2028, “They see this coming. I expect to see very thoughtful ideas coming from them.”

The online prediction markets are giving Proposition 40 only about a thirty-per-cent chance of passing. If polls show that it has a slight advantage, how can that be? The markets price in a number of other factors—most obviously the opposition’s advertising campaign, which will go largely unanswered because the proponents of Proposition 40 used up most of their cash to gather signatures to get it on the ballot. The first round of opposition ads leaned heavily on a study published by economists at the Hoover Institution, a Stanford-based conservative think tank; they envision an “Atlas Shrugged” scenario in which Proposition 40 drives so many billionaires out of California that, rather than raising a hundred billion dollars for the state, it leads to twenty-five billion in lost tax revenue. During the final weeks of the campaign, the initiative’s proponents will have to rely on person-to-person organizing.

Regan, who’s never hesitant to think big, told me he is confident that this can work: “If you can find a million people to turn out ten people each, that’s ten million votes. Seven million votes wins. That’s what we’re trying to do. It’s never been done at this level, in the history of American politics.”He said it’s not out of the question that he gets the Pope’s endorsement.

These are legal questions. For now, political questions are far more important. Imagine the soon-to-arrive moment when Anthropic goes public, creating, overnight, multibillion-dollar fortunes just as the public is turning against A.I. (OpenAI, evidently aware of this dynamic, has announced that it will not go public this year.) Imagine a Democratic Presidential primary in which Newsom feels compelled to propose a national wealth tax because he promised to do so instead of endorsing Proposition 40.

Dan Newman, a veteran Democratic political consultant in California who is working for the opposition to Proposition 40, told me, “It’s going to be a raise-your-hand moment at the early Democratic-primary debates”—no candidate in the field will be able to duck the question entirely. They will have to weigh the power of voters’ anti-billionaire mood against the value of the Democrats’ relationship with Big Tech. Endorsing wealth taxes could also imperil the Party’s relationship with the Brahmin left, which is reliably liberal on social issues but not necessarily on economic ones, and which might not believe that non-billionaires will be spared significant new taxation.