These days in the United States, the word on most lips is: hope. It was the key word in the mammoth ceremonies that marked the accession of Barack Hussein Obama to the presidency on Tuesday. It was also the main theme of the tsunami of media commentary that has preceded and accompanied the historic event. And it is the word that a visitor hears most often from ordinary citizens.

What is surprising is that Americans have latched onto hope at a time that they face what seems like a major economic recession while their nation is engaged in a global war against enemies whose profile remains as murky as ever.

Six years ago the word on most American lips was fear. That, too, was surprising if only because the American economy at the time was heading towards the biggest boom it had experienced since the 1940s while American arms were triumphant in Afghanistan and Iraq.

The experience of the past six years has shown the limits of fear as a mobilizing theme. In 2001, fear brought Americans together in what they saw as a war of self defense in Afghanistan. In 2003 it provided them with enough unity to make the war in Iraq possible. By 2005, however, it was clear that, as a unifying theme, fear was becoming subject to the law of diminishing returns.

Obama owes his surprise election victory to a rejection of the theme of fear by a majority of Americans.

On Tuesday, as Obama entered the White House, the clock of fear stopped and that of hope started to tick. In time, hope, too, could become subject to the law of diminishing returns. Like its twin of fear, hope could beget either effort or illusion.

It is precisely that outcome which provides the real test of the Obama presidency. Obama could become the leader and symbol of a new national effort or the purveyor of an illusion that could only lead to greater disappointment. As Obama starts his tenure there is as yet no clue regarding which course his presidency might take.

At times he has spoken like a starry-eyed romantic who believes that things are done simply by willing them. The French know this brand of politics as volontarisme: you want something and it is done! When he suggested, in a campaign speech, that his presidency would “stop the oceans from receding”, Obama was the prefect volontarist. He was also a typical volontarist when he claimed that he could solve the most intractable of international problems could be sorted out through talking with adversaries.

Those seduced by Obama’s volontarist streak have helped create a hyper-inflation of expectations that could, in time, harm his presidency.

At the same time, Obama has, on occasions, spoken like a level-headed realist. He has warned Americans that harder days may be ahead and that many of his key promises may well be put on hold for the time being. He has shown signs that he is aware of the fact that hope is a currency that depreciates as fast as fear, of not faster.

This vacillation between volontarism and realism is best illustrated in the administration formed by Obama. He has tried to reconcile fear and hope by creating a team that consists mostly of personalities associated with the administrations of Bill Clinton and George W Bush. According to most sources the only key figure in the new administration to be exclusively loyal to Obama is Ms Suzanne Rice, named US Ambassador to the United Nations.

To be sure, Obama may have formed his administration with a number of tactical points in mind. He may have wanted to unite the Democrat Party which, even after he had won the nomination, remained dominated by the Clinton. He may also have wanted to divide the Republicans by courting the “realists” associated with the first President Bush. Finally, Obama may want to use this team to do the hard work and, inevitably, take the blame. That would enable Obama to strengthen his hold on power, form an administration made of people loyal to him, and move toward implementing his original program.

If that analysis is correct, the first two years of the Obama presidency would be little more than an extension of the Clinton-Bush era. All the radical reforms promised and most of the dramatic changes hinted at would have to wait at least until 2011. By that time, of course, Obama would be heading for his re-election campaign.

To be sure, there is always the possibility that the unexpected, not to mention the imponderable, might intrude at any point to set the agenda as it did in 2001, just months after the start of the Bush presidency.

Obama is already coming under attack from the left wing of his party for his supposed “fear of change.”

One leftist magazine has even dubbed him “Bush III”, pointing out the fact that Obama has adopted Bush’s economic bailout plan and abandoned his own promise of a quick withdrawal from Iraq.

A leading conservative newspaper, on the other hand, has attacked him for not daring to implement his own program.

Obama seems to have decided to ignore the left, at least for the time being. He spent much of his pre-inauguration time courting a number of leading conservative thinkers and columnists. That move seems to have been made on the assumption that his administration is still more threatened from the right than it is from the left.

In the course of time, hope frustrated may prove as dangerous

as fear untamed.