Although “The Wrecking Crew” (Metropolitan Books, 384 pages, $25) purports to be about conservatism, and its many “crimes,” Thomas Frank’s latest is actually far more instructive on the unsettled state of the Democratic Party and its current leftward drift. The author, who created a minor sensation with his best-selling “What’s the Matter With Kansas?” is a trained historian with a pronounced affinity for the Frankfurt School and its neo-Marxist “critical theory” approach to culture and politics. But he writes like a muckraking journalist, and the average reader would have no idea whatsoever that down-to-earth Tom Frank from Mission Hills, Kan., has such a distinguished, if slightly exotic, intellectual pedigree.

Mr. Frank’s point about contemporary conservative politics is straightforward and dogmatic: It lives and breathes to support American plutocracy. The so-called Reagan coalition — including traditional Republicans, Cold Warrior liberals, social conservatives, libertarians, and Carterphobes — was and is merely a carefully calculated narrative designed to win elections:

In America, conservatism has always been an expression of business. Absorbing this fact is a condition to understanding the movement; it is anterior to everything else conservatism has been over the years. To try to understand conservatism without taking into account its grounding in business thought — to depict it as, say, the political style of an unusually pious nation or an extreme dedication to the principle of freedom — is like setting off to war with maps of the wrong country.

That Mr. Frank is setting off to war is an understatement. It would be hard to imagine a more scorched-earth approach to political science. Conservatives are not only wrongheaded, he tells us, but evil manipulators of those poor proles in Kansas who refuse to vote their own economic interests because they insist on honoring their personal values.

If this sounds vaguely like Senator Obama’s formulation on voters who “cling to their guns and religion,” it should come as no surprise. Though the changes are more visible at the congressional level than in the presidential platform of Mr. Obama, we are witnessing a tectonic shift in the Democratic Party from the centrism that President Clinton embraced and imposed on his restive followers to a more open-throated liberalism, now referred to as progressivism, that is angry and spoiling for a fight. The word Mr. Frank uses most often to describe conservatives is cynical, and he doesn’t think they believe in anything much beyond the bottom line. Tellingly, however, he reserves some sharp criticism for the only Democratic president to win two full terms since Franklin Roosevelt, who himself always kept an eye on that bottom line:

Bill Clinton turned out to be the most pro-business Democratic president since Grover Cleveland, and his triumph over more liberal Democrats was a development corporate types wanted to encourage. They were happy to support a Democrat who took their side in NAFTA, welfare and banking deregulation; who eliminated the federal deficit; who retained Alan Greenspan at the Federal Reserve; and who made the chairman of Goldman Sachs his treasury secretary.

Given Mr. Frank’s obsession with the power and ruthlessness of business interests, it’s pretty clear that Mr. Clinton is not on his top-10 list, but he becomes more explicit later, charging that the former president “readily sacrificed his populism on the altar of deficit reduction. He contracted out; he got rough with the federal work force; he even considered privatizing Social Security in his own centrist way.”

One of the author’s articles of faith in this book is that the right deliberately sets out to mismanage and destroy the agencies of government, hence the title. High on the exhibit list is the Katrina disaster, in which the Bush administration clearly failed to distinguish itself. But rather than chalking up this failure to botched leadership and a mismanaged reorganization, which put the Federal Emergency Management Agency under the Department of Homeland Security, Mr. Frank thinks it’s all part of the Republicans’ diabolical plan to discredit government. The most telling element of Mr. Frank’s take on Katrina is what he doesn’t say about the aftermath: The Democratic governor of Louisiana and the Democratic mayor of New Orleans get not one mention, even though most fair-minded observers agreed they were as or even more culpable than the federal officers in charge.

A point of view is expected in political analysis, but lapses such as these undermine Mr. Frank’sargument again and again. A long, and not loving, tour of the Northern Virginia suburbs, with their elaborate mansions and stately office parks, is supposed to indicate the rise of a Republican new-money class — the lobbyists and military contractors who are fueling real estate prices. But the last time I checked, Northern Virginia was trending more Democratic and turning the whole state into a plausible battleground in the coming presidential election. Maybe some of those mansions are occupied by two-bureaucrat couples and lobbyists for Google, Berkshire Hathaway, Fannie Mae, and other businesses and institutions that give so generously to the Democrats.

In fact, the largest misconception Mr. Frank is pushing here and elsewhere is that economic self-interest divides the country neatly between the right and the left. This has never been true and it is certainly not true today, when a plutocrat such as George Soros funds the left and another such as Warren Buffett demands higher taxes for the rich. Why should they be any less “delusional” than a working-class voter who values a candidate’s character more highly than his populism? Mr. Frank may imagine himself a moralist, but he is a materialist at heart.

Mr. Willcox, a former editor in chief of Reader’s Digest, lives in Ridgefield, Conn.