Donald Trump just does what politicians have always done: That, in substance, was Republicans’ defense of their president in the Senate impeachment trial. But there is another interpretation of the Trump presidency, which Andrea Bernstein proposes in her new book, “American Oligarchs: The Kushners, the Trumps, and the Marriage of Money and Power.” Donald, his daughter Ivanka and her husband, Jared Kushner, represent the transformation of our political system into an oligarchy in which narrow circles of family members and business associates exploit public office to amass power and make money. In the words of journalist Sarah Chayes, “Networks made up of top government officials, captains of industry and out-and-out criminals, woven together, are hijacking government and economic function and bending it to serve the purposes of their personal enrichment.”

Bernstein weaves together two narratives: the rise of the Kushner and Trump families from modest immigrant origins to fame and riches, and the rightward shift in the political landscape that made the Trump presidency possible. The vast majority of the text details the questionable deals, political favors, deceptive practices and personal vendettas on which the Kushner and Trump family fortunes were built. This, of course, is not news. A cottage industry of Trump biographers and researchers has uncovered so many examples of deceptive, fraudulent and mean-spirited behavior by the president and his family that one succumbs to outrage fatigue.

The story Bernstein wants to tell, however, is not just about two families but about America, “a tale of specific choices about taxation, regulation, corruption, and campaign finance laws that brought us to where we are today.” In other words, the Trump presidency was a logical outcome of policy changes spearheaded by conservatives (with occasional bipartisan support), including tax cuts and deregulation, and the increasing influence of lobbyists and campaign spending. To make this point, the chronology of the rise of the Trumps and the Kushners is sprinkled with anecdotes about contemporaneous changes in the political landscape: the Reagan tax cuts, financial deregulation, the George W. Bush tax cuts and so on.

Donald Trump, however, was not a creation of the conservative revolution. The business model he inherited from his father, Fred, had been around for decades: Cozy up to local politicians, rake in government subsidies, siphon money out of development projects, bend the law, avoid paying taxes and call in political favors to cover your tracks. Fred got his start by cultivating Brooklyn Democratic Party bosses and lying to a bankruptcy court to buy a failed mortgage business during the Great Depression. Four decades later, Donald leveraged his connections with the mayor and deputy mayor of New York, claimed to have an option agreement he didn’t have and used his father’s financial backing to get a sweetheart deal to redevelop the Commodore Hotel on 42nd Street.

In other words, Trump made his fortune the old-fashioned way: through connections and what some might call corruption. He was supported by the Democratic Party machine in New York, just as Charlie Kushner (Jared’s father) invested in Democratic politicians across the Hudson River. The dubious schemes Trump engaged in — such as trying to get a “blight” designation for part of the Upper West Side so he could benefit from a federal subsidy — are standard currency in the world of retail government capture.

As rich men, Trump and Kushner certainly benefited from the Reagan and Bush tax cuts. But even as they gave more and more money to politicians, they remained largely incidental beneficiaries of the conservative revolution.

The parallel narratives of family and country come together with the presidential campaign and Trump’s election, which Bernstein frames as a capstone to our era of laissez faire, small government and dark money. The Trumps and the Kushners, she writes, “have both benefited from and fueled a system of widening inequality and greater influence of money in politics.”

Trump may be the answer to the past 40 years of political history, but perhaps not in the sense Bernstein describes. For starters, his electoral victory was not a product of unmatched amounts of money: He was outspent by several of his primary opponents (until they withdrew), and he trailed Hillary Clinton badly in both campaign fundraising and external spending.

It is true that conservative leaders — and the billionaires who bankrolled them — set out to lower taxes, slash regulations, install a business-friendly judiciary and eliminate barriers to money in politics. What they produced was one type of oligarchy, which economist Simon Johnson and I described in 2010: a system in which big banks (among other companies) transmuted market power into political power, capturing politicians with fables of their economic importance — and with the prospect of high-paying jobs once they left office. “The Wall Street banks are the new American oligarchy,” we wrote then, “a group that gains political power because of its economic power, and then uses that political power for its own benefit.” The masters of the universe who ran the country’s largest banks had bent public policy to their will for decades, enabling them to earn enormous profits (and bonuses). In 2009, as their highly leveraged bets collapsed around them, they did what oligarchs always do: They shook down the government for a bailout, holding the entire economy ransom. Ah, the good old days.

The oligarchy of the Trumps and the Kushners, however, is something else. Where presidents once waited to leave office before cashing in on the speaking circuit, now the Trump International Hotel in Washington provides a convenient place for domestic supplicants and foreign leaders (and the president’s own inauguration committee) to pay tribute to the Trump family. Where regulators did favors for banks, perhaps hoping for future lobbying jobs, now the president, according to some of his own appointees, demands political favors from foreign governments in exchange for military aid — and gets away with it because the Justice Department and the Senate belong to him.

The replacement of the last decade’s oligarchs by the Trump-Kushner oligarchy is less the natural conclusion to our political drama than a surprise twist in the final act. Trump was clearly not the choice of the business elites who thought they ran the Republican Party and the country. Instead, he is a product of the Faustian bargains that the Republican establishment made along the way. By deploying racism tactically to get out the white vote, they paved the way for a candidate whom white supremacists could claim as their own; by fostering an alternative media universe, they conditioned their base to accept the most ridiculous lies as fact; by undermining and discrediting government, they made it possible for a billionaire showman to run as a truth-speaking outsider promising to drain the swamp.

Finally, Trump’s 2016 victory was a product of our age of rising inequality, but not in the sense that he, as a rich person, benefits from inequality. Indeed, his wealth has been dwarfed many times over by that of the new technology super-billionaires. Instead, with the widening chasm between the very rich and virtually everyone else clear to see, it is easy for ordinary people struggling with economic insecurity to feel that they have been left behind by the march of prosperity, that the system does not care about them.

Trumpism is an example of the alternatives that become conceivable when people have lost faith in their political and economic institutions. The Trump presidency itself only makes it more difficult to restore that faith.

American Oligarchs

The Kushners, the Trumps, and the Marriage of Money and Power

By Andrea Bernstein.

Norton. 484 pp. $30