The Tea Party movement is remarkable in two respects. It is one of the biggest exercises in false consciousness the world has seen – and the biggest Astroturf operation in history. These accomplishments are closely related.

An Astroturf campaign is a fake grassroots movement: it purports to be a spontaneous uprising of concerned citizens, but in reality it is founded and funded by elite interests. Some Astroturf campaigns have no grassroots component at all. Others catalyse and direct real mobilisations. The Tea Party belongs in the second category. It is mostly composed of passionate, well-meaning people who think they are fighting elite power, unaware that they have been organised by the very interests they believe they are confronting. We now have powerful evidence that the movement was established and has been guided with the help of money from billionaires and big business. Much of this money, as well as much of the strategy and staffing, were provided by two brothers who run what they call "the biggest company you've never heard of".

Charles and David Koch own 84% of Koch Industries, the second-largest private company in the United States. It runs oil refineries, coal suppliers, chemical plants and logging firms, and turns over roughly $100bn a year; the brothers are each worth $21bn. The company has had to pay tens of millions of dollars in fines and settlements for oil and chemical spills and other industrial accidents. The Kochs want to pay less tax, keep more profits and be restrained by less regulation. Their challenge has been to persuade the people harmed by this agenda that it's good for them.

In July 2010, David Koch told New York magazine: "I've never been to a Tea Party event. No one representing the Tea Party has ever even approached me." But a fascinating new film – (Astro)Turf Wars, by Taki Oldham – tells a fuller story. Oldham infiltrated some of the movement's key organising events, including the 2009 Defending the American Dream summit, convened by a group called Americans for Prosperity (AFP). The film shows David Koch addressing the summit. "Five years ago," he explains, "my brother Charles and I provided the funds to start Americans for Prosperity. It's beyond my wildest dreams how AFP has grown into this enormous organisation."

A convener tells the crowd how AFP mobilised opposition to Barack Obama's healthcare reforms. "We hit the button and we started doing the Twittering and Facebook and the phonecalls and the emails, and you turned up!" Then a series of AFP organisers tell Mr Koch how they have set up dozens of Tea Party events in their home states. He nods and beams from the podium like a chief executive receiving rosy reports from his regional sales directors. Afterwards, the delegates crowd into AFP workshops, where they are told how to run further Tea Party events.

Americans for Prosperity is one of several groups set up by the Kochs to promote their politics. We know their foundations have given it at least $5m, but few such records are in the public domain and the total could be much higher. It has toured the country organising rallies against healthcare reform and the Democrats' attempts to tackle climate change. It provided the key organising tools that set the Tea Party running.

The movement began when CNBC's Rick Santelli called from the floor of the Chicago Mercantile Exchange for a bankers' revolt against the undeserving poor. (He proposed that the traders should hold a tea party to dump derivative securities in Lake Michigan to prevent Obama's plan to "subsidise the losers": by which he meant people whose mortgages had fallen into arrears.) On the same day, Americans for Prosperity set up a Tea Party Facebook page and started organising Tea Party events.

Oldham's film shows how AFP crafted the movement's messages and drafted its talking points. The New Yorker magazine, in the course of a remarkable exposure of the Koch brothers' funding networks, interviewed some of their former consultants. "The Koch brothers gave the money that founded [the Tea Party]," one of them explained. "It's like they put the seeds in the ground. Then the rainstorm comes, and the frogs come out of the mud – and they're our candidates!" Another observed that the Kochs are smart. "This rightwing, redneck stuff works for them. They see this as a way to get things done without getting dirty themselves."

AFP is one of several groups established by the Koch brothers. They set up the Cato Institute, the first free-market thinktank in the United States. They also founded the Mercatus Centre at George Mason University, which now fills the role once played by the economics department at Chicago University as the originator of extreme neoliberal ideas. Fourteen of the 23 regulations that George W Bush put on his hitlist were, according to the Wall Street Journal, first suggested by academics working at the Mercatus Centre.

The Kochs have lavished money on more than 30 other advocacy groups, including the Heritage Foundation, the Manhattan Institute, the George C Marshall Institute, the Reason Foundation and the American Enterprise Institute. These bodies have been instrumental in turning politicians away from environmental laws, social spending, taxing the rich and distributing wealth. They have shaped the widespread demand for small government. The Kochs ensure that their money works for them. "If we're going to give a lot of money," David Koch explained to a libertarian journalist, "we'll make darn sure they spend it in a way that goes along with our intent. And if they make a wrong turn and start doing things we don't agree with, we withdraw funding."

Most of these bodies call themselves "free-market thinktanks", but their trick – as (Astro)Turf Wars points out – is to conflate crony capitalism with free enterprise, and free enterprise with personal liberty. Between them they have constructed the philosophy that informs the Tea Party movement: its members mobilise for freedom, unaware that the freedom they demand is freedom for corporations to trample them into the dirt. The thinktanks that the Kochs have funded devise the game and the rules by which it is played; Americans for Prosperity coaches and motivates the team.

Astroturfing is now taking off in the United Kingdom. Earlier this month Spinwatch showed how a fake grassroots group set up by health insurers helped shape the Tories' NHS reforms. Billionaires and corporations are capturing the political process everywhere; anyone with an interest in democracy should be thinking about how to resist them. Nothing is real any more. Nothing is as it seems.

• A fully referenced version of this story can be found at www.monbiot.com