It's no more Mr Nice Guy, folks: Bill Clinton must stand his ground or see his economic plan fail, says Rupert Cornwell

In 60 remarkable minutes on Wednesday evening, Bill Clinton transformed America's political and economic debate. His proposal of dollars 500bn of tax increases and spending cuts, his concentration on the deficit above all else, his bald demand: 'Let's just face facts', banished Reaganomics to the history books.

The next most telling moment came a couple of hours after President Clinton had completed his epic speech to Congress. Ross Perot was in a television studio giving the reaction that the White House was awaiting more anxiously than any other. Mr Perot, of course, is rarely given to self-doubt, but shortly after midnight on Wednesday that knowing smile of his was even broader than usual. A prophet had been heeded, beyond even his headiest anticipation.

The emollient Bill had been banished, that pleaser of the presidential election campaign, who bribed the middle classes with promises of renewal without pain. Brimming with energy and conviction, the President embarked on the hardest task of any man who aspires to lead this society of instant gratification: to persuade Americans that pleasure deferred is the essential price of rewards tomorrow. In a word, the political philosophy of Ross Perot.

The plan that Mr Clinton laid out to a joint session of Congress may not succeed. But its sincerity and ambition cannot be questioned, even by those who have cynically chronicled the abandonment of one campaign promise after another, as

Clinton the candidate has metamorphosed into Clinton the President. In dollar terms, the shift from consumption to investment that he is seeking amounts to one of the greatest economic adjustments in modern US history. But he intends even more. Government, the President told his countrymen, is no longer exclusively a problem, but part of the solution as well.

If his word is to be believed, his administration will within months have set out plans for a radical overhaul of the creaking US welfare system and a health care system collapsing under its own weight. The Utopian in Mr Clinton is demanding a clean-up of campaign finance methods that are now perilously close to corruption and, at last, curbs on America's passion for guns. Last but not least, Clinton the moralist wants a new sense of community: 'The test is not what's in it for me, but what's in it for us.' Three decades ago, John Kennedy asked much the same. But if this President has his way, he will have achieved little short of a domestic social revolution.

Never, of course, are instant judgements more hazardous than when they pertain to lofty promises flying in all directions. Days, probably weeks, will be needed to gauge the full impact of the speech and comb through the mountainous explanatory tomes provided yesterday by the White House Budget Office. The devil, Mr Perot presciently warned, is

in the detail. But his language must have been music to the President's ears: 'This was a good first step, I'm very pleased, and our people are very pleased.'

Now the hard part begins. The organised clamour of the lobbyists and groups that will suffer from the dollars 328bn of new taxes has barely started. Mr Perot and other exponents of hair-shirt economics point out that, while tax increases are relatively simple to administer, the hard spending cuts that will ultimately balance them are far less easy to sell, especially to a Congress that is up for re-election in barely 20 months' time. 'Giving Congress more money,' he warned, apropos of the tax increases, in his best line of the night, 'is like taking a friend who's an alcoholic to a liquor store.'

In the end, though, the battle will be won or lost not in Congress, but in the real America Mr Clinton is already visiting. Mobilising a country against an invisible economic enemy is a tricky business - witness Jimmy Carter's forlorn attempt to persuade Americans of the gravity of the energy crisis; the 'Moral Equivalent Of War', remembered now only for its scornful acronym Meow.

Times have changed, however. The second Opec crisis of which Mr Carter warned duly happened. And in their turn, the roaring Eighties have left a bitter taste. This is, as Mr Clinton never tires of saying, the first US generation that fears its children will be worse off than itself. Thanks in good measure to Mr Perot and Mr Paul Tsongas, the average citizen knows, however imprecisely, that Reaganism went wrong, that Washington has gone wrong, and that something must be done. Bill Clinton is gambling all on his ability to harness that mood.

Oddly, the sheer breadth of the sacrifices he is demanding is his best ally. The larger the universe of misery, the harder for individual interest groups - for all their threatened carpet-bombing of Congressional offices and local radio stations by fax, phone and call-in - to argue that they should escape it. Republicans will howl, Wall Street and the wealthy may whine; so may oil men, the coal industry, the Pentagon and defence contractors, old people, the betrayed middle classes, and the bloated health care industry.

Beyond doubt, almighty fights lie ahead.

But consider, as Mr Clinton pointed out, the alternatives: a budget deficit of dollars 600bn plus by the end of the century, when 20 cents of every tax dollar will go on interest payments alone, when health care consumes 20 per cent of the national wealth. 'For 20 years, through administrations of both parties, incomes have stalled and debt exploded. We cannot deny the reality of our condition. We have got to play the hand we were dealt, and play it as best we can.' And yet more will be required: the universal health care coverage under preparation by a task force headed by Hillary Rodham Clinton may cost up to dollars 90bn, entailing - almost certainly - further tax increases.

But Bill Clinton will not be moved, as a small piece of symbolism on Wednesday night demonstrated. Seated alongside the First Lady in the balcony of honour, were no political cronies or family hangers-on. On her left was Alan Greenspan, chairman of the Federal Reserve and guardian of the currency. On her right was John Sculley CEO of Apple Computer, emblem of the hi-tech future in which the US must sink or swim. Silently, Bill Clinton was saying it again: the long-term economic interests of the US are paramount.

And now comes the battle for the hearts and minds of Everyman. To it, this President brings great strengths, but must yet dispel one potentially fatal weakness. After the cackhanded start to his term, Wednesday night was a revelation. In a quintessentially Clinton mix of statistics and Southernisms, he imposed his personality on his office for the first time. Better still, as this master political salesman set off to tout his wares in the Midwest yesterday, he at last had a product to sell. But for all his persuasiveness and grasp of detail, Mr Clinton has still to prove that he shares the capacity of his greatest predecessors, to command not just admiration but fear as well.

All too easily Clinton the nice guy could be perceived by Congress as a soft touch. If so, his entire programme might suffer death by a thousand cuts, which would cumulatively render the final product unrecognisable from the original grand design. In the process he will have squandered a matchless opportunity to forge a new Democratic coalition, blending his party's core constituencies with the gut appeal of Perotism, which could dominate US politics for a generation. For Congress, an entire people and their President, the stakes could hardly be higher.

(Photograph omitted)