After Joe Biden’s fiery speech in defense of democracy last week, most of the Washington press corps responded with another stream of fatuous false equivalencies.

“The Two Parties Finally Agree on Something: American Democracy Is in Danger”, was the headline in the New York Times. A Washington Post editorial declared the president was “wrong to conflate upholding the rule of law with his own partisan agenda, which he called ‘the work of democracy’”.

In his brilliant new book, Dana Milbank, a Post columnist, does not offer any of the squishy-soft judgements to which most of his Washington colleagues have become sadly addicted.

He comes straight to the point that eluded the authors of that Times story and that Post editorial: “Republicans have become an authoritarian faction fighting democracy. There’s a perfectly logical, if deeply cynical reason for this. Democracy is working against Republicans” who have only carried the popular vote once in eight presidential elections since 1988.

As America “approaches majority-minority status”, Milbank writes, “… white grievance and white fear” have driven “Republican identity more than any other factor – and drive the tribalism and dysfunction in the US political system”.

Working as a political columnist for the last 16 years, Milbank has had “a front-row seat for the worst show on earth: the crack-up of the Republican party, and the resulting crack-up of American democracy”.

The book has four roughly equal sections: about the Clinton presidency (“defined by the slashing style of [Newt] Gingrich”), the George W Bush presidency (“defined by the dishonesty of Karl Rove”), the Obama presidency and the era of Trump.

This is meticulous history, showing how the Republicans have spent a quarter of a century “hacking away at the foundations of democracy and civil society”, conducting “their war on truth, their growing exploitation of racism and white supremacy, their sabotage of the institutions … of government, and their dehumanizing of opponents and stoking of violence”.

Milbank traces the Republican love affair with racism back to Richard Nixon’s southern strategy in his 1968 presidential campaign, and dates the beginning of government dysfunction to the four disastrous years from 1995 to 1999 when Gingrich did as much as he could to blow up the federal government when he was speaker of the House.

By showing with minute detail “how extensively Republicans and their allied donors, media outlets and interest groups have been pulling at the threads of democracy,” Milbank makes it clear that the Trump presidency was far from an aberration. It represented the real Republican party, without any of the camouflage of compassionate conservatism.

There was nothing new about Donald Trump’s 30,573 documented lies as president. Gingrich’s Republicans were “saturated with wild, often unsubstantiated allegations. Whitewater. Troopergate. Travelgate. Filegate. Furnituregate. Fallen Clinton aide Webb Hubbell fathered Chelsea Clinton … commerce secretary Ron Brown’s death in a plane crash … was a Clinton-arranged hit”. And so on.

It was Gingrich, the Clinton special prosecutor Ken Starr, his aide Brett Kavanaugh, Rudy Giuliani and Rush Limbaugh who showed Trump “the political power of an endlessly repeated lie”.

The crassness also started with Gingrich.

“I think one of the great problems we have in the Republican party is that we don’t encourage you to be nasty,” Gingrich told college Republicans way back in 1978. “You’re fighting a war. It is a war for power.”

Eleven years later, Gingrich told the reporter John Harwood (who last week left CNN after calling Trump a “demagogue”) Democrats were “grotesque”, “loony” and “stupid”.

Milbank is especially strong about Ralph Reed, “a crucial figure in the perversion of the religious right into an entity more ‘right’ than ‘religious’.” There is also a long recounting of the gigantic lobbying scandal centered on Jack Abramoff and Michael Scanlon, a former top aide to House majority leader Tom DeLay. Scanlon and Abramoff “defrauded Indian tribes to the tune of tens of millions of dollars” by telling them they were promoting their casinos. They also got Reed to mobilize evangelical Christians to oppose gambling projects that competed with his own gambling interests.

Another long section reminds us that the administration of George W Bush actually did even greater damage than Trump, by promoting the lie that Saddam Hussein had weapons of mass destruction and leading America into the completely unnecessary and utterly disastrous war in Iraq.

Milbank’s book is in the fine tradition of It’s Even Worse Than It Looks, the 2012 book by Norman Ornstein and Thomas Mann which was the first to point out the uselessness of the Washington press corps’ attempts to be “fair” to both parties.

Milbank quotes from it: “The Republican party has become an insurgent outlier – ideologically extreme; contemptuous of the inherited social and economic policy regime; scornful of compromise; unpersuaded by conventional understanding of facts, evidence, and science, and dismissive of the legitimacy of its political opposition.”

Herein lies the tragedy of Washington journalism. Ten years after Ornstein and Mann made those astute observations, Milbank is one of just a handful of reporters who have incorporated their wisdom into his work. As a result, he is almost alone in treating the pronouncements of the Republican party with the contempt they invariably deserve.

As Ornstein tweeted on Saturday: “Tragically our mainstream media have shown that they are either AWOL in this battle or have opted on the side of the authoritarians by normalizing their behavior and minimizing their intentions.”

• The Destructionists: The Twenty-Five Year Crack-Up of the Republican Party, is published in the US by Doubleday