Mr Bush has emerged by an almost mystical process as strong favourite for the Republican nomination but has yet to be tested on the road outside his home state. Yesterday he began shaping a political vision that could persuade voters to send him in his father's footsteps to the White House.
He kicked off his campaign with a swing through Iowa, which will be one of the first states to give an indication of its political favourites. With over a year to go before America's elections, the sound and fury of a campaign is already rising in the Mid West. Candidates have stomped around the state all week kicking up the dust in any way they can. They have tentatively begun to engage each other in scraps that foreshadow the larger battle ahead, with the Texas governor the most obvious target.
In speeches prepared for his first outing as a candidate, Mr Bush tried to flesh out his idea of "compassionate conservatism", which has been criticised by his opponents as too vague. He promises "prosperity with progress", mixing a commitment to free markets with a zeal for educational and social reform, but always emphasising individual and community action over government. Over the coming weeks, Mr Bush's supporters and opponents alike will demand that flesh be put on these bones.
Advisers stress that Mr Bush's ideology has a strong religious underpinning - a welcome message in a devout state. "Compassionate conservatism, an outgrowth of Christian principles, sees the failure of liberal approaches and promotes effective ways of helping the poor," said Marvin Olasky, a senior fellow with the Acton Institute for the Study of Religion and Liberty, and a Bush advisor. "I think he understands that it is effective because it is based on biblical understandings, and God is smarter than even the brightest of our social planners."
With a solid poll lead, modesty is the order of the day for Mr Bush. "I know I've got a lot of work to do," he told the Des Moines Register in an interview. "I'm committed to setting up not only a great organisation in Iowa, but being there to help begin the fires of enthusiasm and turn out the vote." Mr Bush's vast cash pile is expected to reach $20m (pounds 12.5m) when fundraising figures are disclosed next week, but Iowa is a state where retail politics is still important.
In August, Iowa Republicans vote in a "straw poll" that gives a sense of where the party wants to put its mark; and next year, the state is amongst the first to hold party caucuses that determine the candidates. Under lowering grey skies, Mr Bush set out to charge through the state at maximum speed, attending fundraisers and addressing invited guests and the press. It is a preview for a selected audience.
Eager politicians have been drawn to Iowa all week by the prospect of the World Pork Expo, an annual gathering that brings thousands of pig farmers and families hungry for barbecued baby back ribs to the state fair ground in Des Moines. As well as cooking demonstrations, pig races and the Pig-casso art exhibit, they were due to be visited yesterday by Elizabeth Dole and John Kasich, two other Republican candidates, as well as Mr Bush. Mrs Dole comes a distant second to Mr Bush in early polls, while all other candidates lag even further behind.
His rivals are already sniping at Mr Bush. Gary Bauer, a religious activist, challenged Mr Bush to make his stand on abortion clear by pledging to appoint only anti-abortion judges. "The governor refuses to say what his tests will be," he told the Bull Moose Club, a local Republican organisation. Pro-choice groups, similarly, are demanding that he clarify his position, but he is likely to satisfy neither.
Until now, Mr Bush, 53, has stayed in Austin, his state capital, building his political base and assembling a formidable team of advisors and fundraisers. Karl Rove, his brilliant if Machiavellian political strategist, put together a campaign that appeared to make Mr Bush the anointed candidate before he had even declared an interest in running. He is not going to ruin everything now by detailing his positions to satisfy his adversaries.
From the wide open plains of Iowa, Mr Bush flies on to the rocky coast of Maine, where he will celebrate his father's 75th birthday at the plush family estate in Kennebunkport. It is but a short drive from there to New Hampshire, where he will try to woo the nation's other early primary state. But whereas Iowa is very keen on Mr Bush, New Hampshire - which is more right-wing - is less easily persuaded of the virtues of compassionate conservativism.
As Mr Bush returns to the colonnaded splendour of the gubernatorial mansion on Colorado Street in Austin, his most likely opponent, Al Gore, will leave the White House to proclaim his own candidacy. Mr Gore will make a symbolic visit to his home state, Tennessee, to declare. "This is the week the big dogs start to bark," said the Washington Post.
But there is a curious emptiness to Mr Bush, which may fill as the campaign progresses. Despite his formidable strengths as a candidate, he has yet to express precisely why he believes that he, and he alone, should be the next President. David Yepsen, the veteran political correspondent of the Des Moines Register, sensed this lack of focus. "He did not seem driven to be President," he noted.