With a foreword from Robert F Kennedy Jr, David Stockman, once Ronald Reagan’s budget director, delivers an unsparing attack on Donald Trump. The former president’s stances on trade, social security, spending and Covid all receive a beatdown. Stockman was somewhat sympathetic to Trump when he rose to power eight years ago but has since grown hostile, posing as a keeper of the flame of Reaganism, defender of free markets and opponent of statist encroachment.

Stockman’s plug from RFK Jr, a former candidate for the Democratic presidential nomination now running as an independent, is noteworthy. After reminding the reader of past antipathy toward Stockman over cuts to the Environmental Protection Agency budget four decades ago, Kennedy lauds him for criticizing Trump on Covid.

“He’s truth-teller,” Kennedy declares. “He tells the truth in these pages – by the numbers.”

In 2007, the Securities and Exchange Commission filed civil fraud charges against Stockman, together with officers and employees of Collins & Aikman, an auto-parts supplier that went bankrupt in 2005.

“Between 2001 and 2005, C&A and several of its former officers and employees, including its chief executive officer, Stockman, engaged in pervasive accounting fraud,” the commission alleged. The case was settled in 2010, after Stockman agreed to pay $7.2m, without admission of wrongdoing.

As for Kennedy, he has problems of his own.

“Covid-19. There is an argument that it is ethnically targeted,” he said in Manhattan last year. “Covid-19 is targeted to attack Caucasians and Black people. The people who are most immune are Ashkenazi Jews and Chinese.”

For the record, Borough Park and Midwood in New York, home to large Jewish populations, had among the highest Covid death rates in the city. Both neighborhoods also had markedly low vaccination rates.

Despite his protestations to the contrary, Kennedy sure looks like an anti-vaxxer. In states and cities, the red v blue, Republican v Democrat Covid death rate disparity is real. Ditto the gap in vaccine hesitancy.

More comically, Kennedy’s campaign recently announced that he would not attend a birthday party fundraiser after several celebrities supposedly due to be there said they had nothing to do with the bash.

“I don’t know anything about this event,” the singer Dionne Warwick said. “I did not agree to it, and I certainly won’t be there.” The actor Martin Sheen announced: “I wholeheartedly support President Joe Biden and the Democratic ticket in 2024.”

Back to Stockman. Since 2017, in his eyes, Trump has repeatedly failed. In 2019, Stockman wrote Peak Trump: the Undrainable Swamp and the Fantasy of Maga, in which he called Trump “a political flyweight, megalomaniacal incompetent and bile-ridden bully who stumbled into the Oval Office”.

On the eve of the 2020 election, Stockman exhorted conservatives to abandon Trump. “[His] embrace of what amounts to crackpot economics has not only left the nation spiraling toward the mother of all financial disasters,” Stockman wrote. “He has also finally euthanized what remained of GOP fiscal rectitude.”

Really? With Reagan as president and Stockman at the Office of Management and Budget, the federal deficit ballooned to nearly 5.9% of GDP, a post-second world war record. “Reagan proved deficits don’t matter,” Dick Cheney gushed in 2003, as vice-president, staring at tax cuts passed under his boss, George W Bush.

On Trump’s watch, the deficit-GDP ratio came within a whisker of 14.9%. Even before Covid, Trump was visibly unconcerned with federal spending – unless it was part of the legacy of Barack Obama.

“It’s a great talking point when you have an administration that’s Democrat-led,” said Mark Walker, a former North Carolina Republican congressman and minister, in 2017. “It’s a little different now that Republicans have both houses and the administration.”

Under Biden, the deficit stands at around 5.5% – evoking Republican howls. Then again, Reagan and the Federal Reserve did manage to tame inflation. By contrast, Biden underestimated the inflationary impact of his spending and interest rates remain stuck. Said differently, a trip to the supermarket is a constant and nagging problem – a reality-based Trump ad.

Stockman also criticizes Trump for his aversion to cutting benefits for seniors – which puts the likely Republican nominee in sync with the American public.

“With the Donald’s loud insistence, the contemporary GOP has even taken a powder completely on Medicare, social security and the lesser entitlements,” Stockman writes. His solution: “Import millions of new workers.” Will the Republican party of Trump ever choose to take such medicine? Not likely.

In a sense, Stockman is simply being Stockman, an ideological vagabond searching for a cause. In high school, he entered an American Friends Service Committee essay contest and won with “an ode to Martin Luther King Jr and Mahatma Gandhi”, Peter Steinfels, a noted Catholic liberal and journalist, recalled.

But Stockman also helped Barry Goldwater’s ultra-conservative campaign for president in 1964. Later, in college, he struck a pose as a Students for a Democratic Society, anti-Vietnam war activist. He moved on to become a Reagan-era supply-sider, then a fiscal conservative. In the late 1970s and early 1980s, as a congressman, Stockman was the sole member of the Michigan delegation to oppose a government bailout of Chrysler.

Taken together, all this makes Kennedy’s praise for Stockman politically self-destructive. The idea of a Democrat-turned-independent presidential candidate pumping a book that calls for cuts to social security and increased immigration is down-right wacky. Talk about anti-populism. Seniors vote. Other than publicity, there is little to be visibly gained.

And yet, our political system ails. Five in eight Americans say they back a third party, including three-quarters of independents and 58% of Republicans. Trump and Biden are viewed unfavourably, the president in a double-digit pit. Kennedy’s numbers remain above water, which may be an accomplishment in itself. He may be more of a threat to Trump than to Biden. In the end, Stockman will be rooting for him.

• Trump’s War on Capitalism is published in the US by Skyhorse