All of a sudden, President George Bush looks as vulnerable as his father

Only Harry Truman among incumbents has overturned this sort of deficit at this stage of the electoral cycle

For the House of Bush, elections are hardball. At regular intervals in the 1980s and early 1990s, that Republican country club gentleman George Herbert Walker Bush would disdainfully enter what he called "full campaign mode." What he meant was the temporary abandonment of the lofty peaks of government for the down and dirty ritual of ensuring the family's right to rule.

Thanks in good measure to a certain Lee Atwater, a campaign adviser with good ol' boy manners and an unrivalled instinct for the political jugular, the tactic worked. In the 1988 presidential election, the political machine of Bush père made mincemeat of the wretched Michael Dukakis. Similar tactics might have worked in 1992, had Atwater not died of a brain tumour the previous year, and the elder Bush not trusted so greatly in the divine right of kings - only to find himself up against Bill Clinton, the finest natural politician of the age.

Now it is the turn of the son, and the only difference is that the process has started much sooner. George H W Bush preferred to put off the distasteful necessity of "campaign mode" until the summer of election year. In his speech to Republican governors on Monday evening however, George W Bush kicked off his campaign even before winter was done.

One reason for the early start is that the younger Bush is a much better politician than his father. Bush senior might have forgotten more about international affairs and the world beyond America than the son has yet learnt. But when it comes to the hard graft of politics - securing your base, building networks, raising money and delivering quid pro quos - Bush junior leaves Bush senior trailing.

There is, of course, another reason: the spectre of what happened 12 years ago. In 2000, the Bush restoration was secured. But a nightmare haunts this American dynasty. One single-term Bush presidency might be ascribed to carelessness. A second would be a family humiliation. All of a sudden, however, the prospect is not to be ruled out.

A couple of months ago, Bush appeared on a glide-path to re-election. Saddam Hussein had been captured, while the Democrats were poised to commit political hara-kiri by nominating the pleasingly angry but thoroughly unelectable Howard Dean. Now the picture is transformed. Dean is history. George W's opponent will be a polished and practised Senator - most probably the gravitas-laden John Kerry of Massachusetts, just possibly the youthful and nimble John Edwards of North Carolina.

Much is in this Bush's favour. He has the power of incumbency, and the economic cycle is much kinder. A dozen years ago, at this point in the campaign, a recession was just ending. This time, a solid recovery is underway. Interest rates are historically low, while skyrocketing budget and trade deficits alone never cost a sitting president the White House. But the polls tell a different story.

An astonishingly positive primary season, in which the candidates have weighed into Bush rather than each other, has galvanised the Democrats, while Saddam's non-existent WMD and the mess on the ground in Iraq have put the White House on the defensive. The President's limp and fumbling performance in a TV interview that was supposed to set the record straight only made matters worse.

For the time being, at least, this Bush looks as vulnerable as his father. Gallup/CNN last week found that either Kerry or Edwards would win a presidential election today by 10 points. A single poll to be sure - but remember that since the Second World War, only Harry Truman among incumbents has overturned this sort of deficit at this stage in the electoral cycle.

Not surprisingly, the White House has moved up its counter-offensive from the early summer to now. And equally unsurprisingly, students of the Bush family's political modus operandi are already predicting one of the roughest, nastiest elections in modern US history.

The technique was perfected by Bush père, and will be followed by the son. Ensconced in the White House, the President will take the high ground, projecting competence, re-assurance and optimism. Meanwhile, his top political strategist Karl Rove and his minions - the Lee Atwaters of their day - will take care of the slash-and-burn side of proceedings.

In fact, John Edwards, with his southern charm, his cheerful message and relatively short career in Washington, is the Democrat the White House secretly fears the most. Kerry, though, is another matter. This Bush machine is confident it can take a wrecking ball to the latter's candidacy - just as Atwater destroyed Dukakis in 1988, portraying him as a soggy north-eastern liberal out of touch with the "real America".

Armed with a campaign war-chest of $130m and counting, the Bush campaign will seek to define Kerry in the same terms, very early and very vigorously. For Republican "opposition research" specialists, the thousands of votes cast by Kerry over two decades in the Senate already provide endless material to depict him as weak on national security and defence, and as a Dukakis redux on domestic policy. They will torture him on wedge issues like gay marriage, which split Democrats down the middle.

In his speech to the governors, the President served up an aperitif, not mentioning Kerry by name, but accusing him of waffling and flip-flopping on issues from Iraq to free trade. The contrast will be fleshed out by the television ad campaign that starts next week, promoting a serene and decisive president protecting the country from terrorists and wicked foreign dictators.

Kerry vows to fight back, brandishing his Vietnam medals, and surrounding himself with his "band of brothers" from the Navy swift boats in the Mekong delta. But for Bushes, all is fair in election season.

Whether the hand of Rove and his underlings was behind the adultery smear against Kerry, and the doctored photos showing him alongside Jane Fonda, is unproven, and in any case neither has had much effect. No amount, however, of silver and bronze stars for valour may be enough to protect Kerry. John McCain, too, was a Vietnam hero. But when it seemed possible he might snatch the Republican nomination in 2000, that did not prevent surrogates of a candidate who spent that war in the Texas National Guard from portraying him as an enemy of veterans, and launching a slanderous whispering campaign about McCain's private life.

Alternatively, consider the case of Democrat Max Cleland, who lost three limbs in Vietnam, yet lost his Senate seat in Georgia in the 2002 mid-term elections as Republicans ran a vicious campaign, claiming he was soft on security.

Yes, this Bush is vulnerable. The deceits over Iraq, as well as repeated and absurd claims about jobs and runaway deficits have eroded the reputation for trustworthiness that was his most precious political asset. But Democrats beware. When it comes to "full campaign mode", you ain't seen nothing yet.