WASHINGTON: The prevailing political wisdom is that the economy — not foreign policy — will determine who becomes the next president of the United States.

When voters were asked in a Washington Post-ABC News poll this week what the single most important issue was for them in choosing a president, 52 per cent said jobs and the economy (and they're evenly split on whether Barack Obama or Mitt Romney would do a better job on the latter).

To put that figure in perspective, the second most-cited issue was “Health care/repealing Obamacare” at a mere 7 per cent, while foreign-policy issues such as terrorism and the war in Afghanistan each mustered a measly 1 per cent of responses. In January, the Pew Research Centre concluded that the American public is more concerned with domestic policy than at any point in the past 15 years.

But every politician lives in fear of that 3am phone call that can upend the best-laid campaign plans. Here are some global events that could send the US election careening along a very different path than the one it's travelling down today.

A showdown with Iran

World powers are currently wrapping up a second round of contentious nuclear talks with Tehran, and the European Union is preparing to roll out an oil embargo on Iran in July. But if this diplomatic tack fails to wring meaningful concessions from Iran, there's an outside chance that Israel — or, in a less likely scenario, the United States and its allies — will conclude before November that military action is the only way to halt Iran's nuclear advances (some have even suggested that it's in the interests of Israeli leaders to strike Iran's nuclear facilities in the run-up to the US election). Americans see Iran as the country that represents the greatest threat to the United States, and a recent Pew poll found that 63 per cent of Americans are willing to go to war if necessary to prevent Iran from developing nuclear weapons — a measure that Romney has promoted more aggressively than Obama, though both candidates have said that all options are on the table.

Some market analysts estimate that a military conflict with Iran could push gas prices in the United States to between $5 and $6 per gallon, alienating voters and jeopardizing the country's fitful economic recovery. And there's a reason why the National Journal's Charlie Cook has dubbed Iran the "wild card" this campaign season: The last five times gas prices have spiked during a US presidential campaign, the incumbent party has lost the election. As The New York Times put it in January, the standoff with Iran presents Obama “with choices that could harm either the economic recovery or his image as a firm leader”.

A European nosedive

The prospect of a Greek anti-austerity party winning new elections in June has sparked widespread fear that Greece will default on its debt and exit the eurozone, which could spread contagion in southern Europe and plunge the global economy back into recession. But there's a debate about the extent to which the European debt crisis will influence the US election.

If a Greek exit precipitates the collapse of the eurozone, Brookings Institution scholar William Galston argues in the New Republic, it will be disastrous for Europe and the United States. But he adds that US GDP growth would probably slow and the unemployment rate would likely stagnate even if the European monetary union remains intact after Greece's departure. "These developments would make it harder for Obama to argue that we're heading in the right direction, and . . . I suspect that economic growth at these depressed levels would mean victory for Mitt Romney," he writes.

Or, as The Washington Post's Ezra Klein noted earlier this year, Obama's re-election "will be largely decided by the state of the economy. And the state of the economy will largely be decided by events in Europe. And Europe's not looking so good."

But others argue that Greece won't drop out of the eurozone before November, if it does so at all, or that the American financial system isn't particularly vulnerable to a Greek exit.

A Chinese economic slowdown

China’s slowing economic growth — which dropped to a nearly three-year low of 8.1 per cent in the first quarter of 2012 — has prompted Chinese leaders to pledge new measures to stimulate domestic demand and commentators to warn of an impending economic crisis in the country. This week, the World Bank cut its growth forecast for China and cautioned that a recession in Europe could take a heavy toll on the Middle Kingdom, which in turn could stifle growth in other East Asian nations.

But when Beijing sneezes, does Washington catch a cold? China's sluggish growth poses a "substantial risk" to the United States as the general election approaches, Campbell Harvey, a professor at Duke University, told CNN this week. "You don't need a lot to knock us out of recovery."

A domestic terrorists attack

The United States has not suffered a major terrorist attack during Obama’s presidency, and the administration has foiled several plots — most recently an attempt by Al Qaeda in the Arabian Peninsula to bomb a US-bound plane. The president has taken out several high-profile terrorists through drone strikes and touted the killing of Osama bin Laden as one of his signal achievements — much to Mitt Romney's chagrin.

But an attack on American soil could instantly shatter the armour Obama has built up on national security, reverse the public's declining concern about terrorism, and transform the campaign. And such a scenario isn't out of the question. Two of the most high-profile attacks in recent years — the Christmas Day bombing attempt in 2009 and the Times Square bombing attempt in 2010 — were thwarted by luck as much as anything else, with the perpetrators failing to detonate their explosives (and, in the case of the Times Square bomber, a street vendor spotting a smoking SUV).

As The Washington Post's Chris Cillizza and Aaron Blake recently pointed out, foreign policy has proven pivotal in only one of the last five presidential elections: the 2004 contest, which was the first race after the worst terrorist attack on American soil in US history. And we all know how that one turned out.

By arrangement with the Washington Post/Bloomberg News Service