The actress Shirley MacLaine once said, “It’s useless to hold a person to anything he says while he’s in love, drunk or running for office.” Mitt Romney has certainly said everything to throw voters off the trail. Reactionary Romney, the self-proclaimed “severe conservative” of the primaries, overnight became Moderate Mitt, an ultra-reasonable guy who says there is little difference between him and Barack Obama except competence.

If Romney’s rebranding tricks the people and he wins on 6 November, he will soon discover what it is like to be Obama, a president hemmed in by hostile forces. Since angry Tea Party activists consumed the Republican Party in 2009- 2010, candidates and congressmen have lined up to sign pledges promising that, if elected, they will not compromise on introducing tax cuts, public spending caps and a constitutional amendment to balance the federal budget, and will agree to outlaw abortion, ban pornography and keep women in uniform off the front line.

Grover Norquist, leader of the anti-tax group Americans for Tax Reform, has gone further. If he has his way, Romney, who is neither liked nor trusted by Tea Party true believers, will have little say over what happens in a Romney administration. Norquist has championed what amounts to a parliamentary revolution. “The leadership now for the modern conservative movement for the next 20 years will be coming out of the House and the Senate,” he told a conservative conference this year. “We don’t need a president to tell us in what direction to go. We just need a president to sign this stuff . . . Pick a Republican with enough working digits to handle a pen.”

Chinese roulette

Romney the human windsock does not appear too worried about becoming Romney the rubber stamp. He is prepared to say and do anything, so long as he and his family are allowed to live in the White House. So what do Republican radicals have in store in the event of victory? And how will it affect the rest of the world?

Romney has assembled a transition team, grandly called “the Readiness Project”, to transform America from what many conservatives believe has become a Europe-style social democracy into a free-market nation fit for businessmen and entrepreneurs. First, Republicans in Congress will pass a law to avoid the “fiscal cliff”, the automatic deep cuts to public spending and lapse of the Bush tax cuts that was the price of keeping the federal government solvent in the summer of 2011.

The grand bargain will reduce income taxes to 20-25 per cent across the board and take a cleaver to entitlements for the poor, the elderly, the disabled and the disadvantaged. Romney has already signed up to his running mate Paul Ryan’s budget plan, which, according to estimates, would give 37 per cent of tax cuts to those earning more than $1m and cut benefits for the poor by 62 per cent. Ryan suggests cutting Medicaid – medical care for those who cannot afford health insurance – by 75 per cent. Meanwhile, taxes on dividends will be abolished, business regulations minimised and environmental restrictions and employment laws eased. If America is to compete with China, Romney suggests, US labour costs and employee protections must match those in China. Welcome to the 19th century.

Romney says he cannot specify how the tax cuts will be paid for but he will overhaul the tax code and cut deductibles. He may put a ceiling – $25,000 has been mentioned – on all personal tax breaks. The government will shrink in size. State-funded programmes in line for a haircut include public education, public safety measures, public transport, used largely by the less well-off, and scientific research. Romney also wants to end federal grants to public television, though it would save only $223m annually, and privatise Amtrak, the state-owned rail network.

Romney’s gamble follows David Cameron’s and George Osborne’s lead. He believes – it is an act of faith, not economics – that cutting government, taxes and regulations will spur Americans to become more entrepreneurial and thereby create jobs. Yet slashing government spending would likely tip the economy into a double-dip recession, just as it did in the UK and Italy. So far, with the eurozone and austerity Britain in the doldrums, the world economy is being kept afloat by slender US growth. Even if, as promised, Romney eventually spends $2trn more on defence to pursue a more aggressive neoconservative foreign policy, the sudden removal of trillions of federal dollars from US GDP will drive the whole world into a slump. That is what is at stake on 6 November.

Judge dread

There is more. Republicans wish to impose their reactionary social agenda on the half of the US they disagree with. Romney has said he would be happy to sign a law making all abortion illegal in all circumstances, including cases of rape and incest and when the procedure is necessary to protect a mother’s health. If that were to happen, Mexico and Canada (perhaps the UK, too) would become medical refugee destinations for those who can afford the air fare. American women who travel abroad to abort can expect to be arrested for murder on their return.

Reactionary Supreme Court rulings can be expected, including judgments reversing landmark civil rights, gender equality and sexual orientation legislation, if Romney replaces retiring justices with conservatives. Four are in their seventies, including the liberal Ruth Bader Ginsburg, aged 79, who has wanted to stand down since having part of her spleen and pancreas removed in cancer surgery in 2009.

The court is already finely balanced, with an old, moderate Republican, Anthony Kennedy, aged 76, usually tipping the balance in favour of liberal decisions.

That is just the start. If the Senate becomes Republican, both houses of Congress, the court and the presidency will all be in the hands of conservatives and there will be no check on what they enact. So much for the division of powers envisaged by the Founding Fathers. That is the precipice over which Americans are peering in fear this election.