Since the election of Barack Obama, the Republican Party has proved that one of its central intellectual arguments was right all along. It has long claimed that evolution is a myth believed in only by whiny liberals – and it turns out it was on to something. Every six months, the party venerates a new hero, and each time it is somebody further back on the evolutionary scale.

Sarah Palin told cheering rallies that her message to the world was: "We'll put a boot in your ass, it's the American way!" – but that wasn't enough. So the party found Michele Bachmann, who said darkly it was an "interesting coincidence" that swine flu only breaks out under Democratic presidents, claims the message of The Lion King is "I'm better at what I do because I'm gay", and argues "there isn't even one study that can be produced that shows carbon dioxide is a harmful gas."

That wasn't enough. I half-expected the next contender to be a lung-fish draped in the Stars and Stripes. But it wasn't anything so sophisticated. Enter stage (far) right Donald Trump, the bewigged billionaire who has filled America with phallic symbols and plastered his name across more surfaces than the average Central Asian dictator. CNN's polling suggests he is the most popular candidate among Republican voters. It's not hard to see why. Trump is every trend in Republican politics over the past 35 years taken to its logical conclusion. He is the Republican id, finally entirely unleashed from all restraint and all reality.

The first trend is towards naked imperialism. On Libya, he says: "I would go in and take the oil... I would take the oil and stop this baby stuff." On Iraq, he says: "We stay there, and we take the oil... In the old days, when you have a war and you win, that nation's yours." It is a view that the world is essentially America's property, inconveniently inhabited by foreigners squatting over oil-fields. Trump says America needs to "stop what's going on in the world. The world is just destroying our country. These other countries are sapping our strength." The US must have full spectrum dominance. In this respect, he is simply an honest George W Bush.

The second trend is towards dog-whistle prejudice – pitched just high enough for frightened white Republicans to hear it. Trump made it a central issue to suggest that Obama wasn't born in America (and therefore was occupying the White House illegally), even though this conspiracy theory had long since been proven to be as credible as the people who claim Paul McCartney was killed in 1969 and replaced with an imposter. Trump said nobody "ever comes forward" to say they knew Obama as a child in Hawaii. When lots of people pointed out they knew Obama as a child, Trump ridiculed the idea that they could remember that far back. Then he said he'd "heard" the birth certificate said Obama was Muslim. When it was released saying no such thing, Trump said: "I'm very proud of myself."

The Republican primary voters heard the message right: the black guy is foreign. He's not one of us. Trump answered these charges by saying: "I've always had a great relationship with the blacks."

The third trend is towards raw worship of wealth as an end in itself – and exempting them from all social responsibility. Trump is wealthy because his father left him a large business, and since then companies with his name on them have crashed into bankruptcy four times. In 1990, the Pulitzer Prize-winning journalist David Cay Johnston studied the Trump accounts and claimed that while Trump claimed to be worth $1.4bn, he actually owed $600m more than he owned and you and I were worth more than him. His current wealth is not known, but he claims he is worth more than $2.7bn.

Johnston says that in fact most of Trump's apparent fortune comes from "stiffing his creditors" and from government subsidies and favours for his projects – which followed large donations to the campaigns of both parties, sometimes in the very same contest. Trump denies these charges and presents himself as an entrepreneur "of genius".

Yet for the Republican Party, the accumulation of money is proof in itself of virtue, however it was acquired. The richest 1 per cent pay for the party's campaigns, and the party in turn serves their interests entirely. The most glaring example is that they have simply exempted many of the rich from taxes. Johnston studied four of Trump's recent tax returns, and found he legally paid no taxes in two of them. In America today, a janitor can pay more income tax than Donald Trump – and the Republicans regard that not as a source of shame, but of pride.

How are these tax exemptions for the super-rich paid for? Here's one example. The Republican budget that just passed through the Senate slashed funding to help premature babies to survive. The rich riot while the poor shrivel. Trump offers the ultimate symbol of this: he won't even shake hands with any ordinary Americans out on the stump, because "you catch all sorts of things" from them. Yes: the Republican front-runner is a billionaire who literally won't touch the poor or middle class.

The fourth trend is to insist that any fact inconvenient to your world view simply doesn't exist, or can be overcome by pure willpower. Soon, the US will have to extend its debt ceiling – the amount of money the government is allowed to borrow – or it will default on its debt. Virtually every economist in the world says this would cause another global economic crash. Trump snaps back: "What do economists know? Most of them aren't very smart." Confront the Republicans with any long-term social or economic problem, and they have one response: it would go away if only we insisted on our assumptions more aggressively.

This denial of reality runs deep. So Trump says "it's so easy" to deal with rising oil prices. He says he would call in Opec, the cartel of oil-producing nations, as if they were contestants on his show The Apprentice, and declare: "I'm going to look them in the eye and say, 'Fellows, you've had your fun. Your fun is over.' "

It's the same, he says, with China. He will order them to stop manipulating their currency. When he was informed that the Chinese had some leverage over the US, he snapped: "They have some of our debt. Big deal. It's a very small number relative to the world, ok?" This is what the Republican core vote wants to be told. The writer Matthew Yglesias calls it "the Green Lantern Theory of Geopolitics". It's named after the Marvel comics superhero the Green Lantern, who can only use his superpowers when he "overcomes fear" and shows confidence – and then he can do anything. This is Trump's view. The whiny world simply needs to be bullied into submission by a more assertive America – or the world can be fired and he'll find a better one.

Trump probably won't become the Republican nominee, but not because most Republicans reject his premisses. No: it will be because he states these arguments too crudely for mass public consumption. He takes the whispered dogmas of the Reagan, Bush and Tea Party years and shrieks them through a megaphone. The nominee will share similar ideas, but express them more subtly. In case you think these ideas are marginal to the party, remember - it has united behind the budget plan of Wisconsin Representative Paul Ryan. It's simple: it halves taxes on the richest 1 percent and ends all taxes on corporate income, dividends, and inheritance. It pays for it by slashing spending on food stamps, healthcare for the poor and the elderly, and basic services. It aims to return the US to the spending levels of the 1920s – and while Ryan frames it as a response to the deficit, it would actually increase it according to the independent Center for Budget and Policy Priorities. Ryan says "the reason I got involved in public service" was because he read the writings of Ayn Rand, which describe the poor as "parasites" who must "perish", and are best summarized by the title of one of her books: 'The Virtue of Selfishness.'

The tragedy is that Obama needs serious opposition – but not from this direction. In reality, he is funded by similar destructive corporate interests, and has only been a few notches closer to sanity than these people. But faced with such overt lunacy, he seems like he is serving the bottom 99 per cent of Americans much more than he really is.