US voters could renew the four-year mandate of President George W. Bush, a plain-talking, "with-me-or-against-me" Texan with no qualms about the use of pre-emptive military force to protect the country.

Or they could replace him with Democratic Senator John Kerry and his more-nuanced view of the war on terror that relies on intelligence, diplomacy and economic clout as much as sheer firepower.

But in a larger sense, today's contest was a struggle for the spirit of the wounded superpower, pitting its democratic traditions and cherished belief in human rights against the most basic of needs to feel safe.

Time magazine summarized the stakes on the cover of one of its pre-election issues: "To the victor goes a nation divided. A nation split over its place in the world, over its basic values, over its future direction."

Not surprisingly, two-third of Americans saw the election as one of the most important -- if not the most crucial -- in their lifetimes, according to a Newsweek poll released over the weekend.

Terrorism and Iraq dominated the first presidential race in 30 years conducted with US troops fighting abroad. The September 11 attacks provided a haunting subtext as both candidates touted their toughness and command credentials.

Bush, unabashedly campaigning as a 'war president" with unfinished work to shore up US defences, told voters: "The outcome of this election will set the direction of the war on terror."

"If America shows any uncertainty or any weakness in this decade, the world will drift toward tragedy," the Republican hammered home in his stump speech. "This is not going to happen on my watch."

Kerry, ridiculed by Bush as weak and waffling on security, also vowed to crush terrorism but placed the emphasis on mending fences with the international community after the contested invasion of Iraq.