By midweek, official results from today's presidential election in the Philippines will be released and how Filipinos voted will have serious consequences for the country and much of South-east Asia.

At stake are the huge gains from the highly successful reform agenda of outgoing President Benigno Aquino's six-year administration, which has turned the Philippines into the region's strongest-performing economy even as the country's importance in geopolitics grows, particularly with regard to what many view as China's expansionist strategy in the region.

The vexing issue in the polls is that the front runner in the multi- cornered contest for the nation's highest office, Mr Rodrigo Duterte, is a deeply polarising figure who will have to contend with vast sections in the country, including the military, who do not approve of his style.

"What we are seeing today is the prospect that the popular candidate is not a politician who has pledged to build on the economic and institutional reforms that have been going on," says a chief executive of a local conglomerate, echoing a widely held view among Manila's powerful business community.

Mr Duterte, the 71-year-old tough-talking mayor of Davao, is riding on a wave of voter dissatisfaction, particularly among the poor and widening middle-class, who insist that they have not benefited from the country's economic gains, and remain upset with crime and rampant corruption.

Most recent opinion polls show Mr Duterte - who has made grand promises such as wiping out crime in three months and amending the Constitution - ahead by 11 percentage points over his closest rival, Senator Grace Poe.

Ordinarily, that margin is enough to secure the presidency. But in the crowded race of five candidates, analysts are not ruling out an upset because roughly 25 percent of voters remain undecided.

Ms Poe and the other high-profile candidate in third place in opinion polls, former interior minister Mar Roxas, are running on platforms to build on the gains of the Aquino administration and on establishing a pro-business environment.

Whatever the outcome, this year's presidential election has renewed foreign investor attention on the Philippines.

Under Mr Aquino, the sprawling archipelago enjoyed political stability and improved governance.

A focused economic reform agenda also helped deliver strong growth, upgrades in its sovereign ratings from international agencies and declining risk premiums to the stock market and the property sector.

The Philippines is the only country in Asean where the ratio of government debt-to-gross domestic product - a measure of a government's ability to repay its debt - has fallen.

From a high of 75 per cent in 2004, it currently stands at 45 per cent, giving the government in Manila more room for direct spending on much-needed improvements to infrastructure.

Several economists argue that the government's strong financial position will help the economy weather any immediate post-election volatility.

What's worrisome, however, is post-election politics.

Several analysts say that Mr Duterte's quick-fix promises during his campaign, such as to cut crime drastically in three months, are not realistic and are likely to lead to public dissatisfaction in the months ahead if he wins office.

His threat to abolish Congress is also likely to bring his opponents together to undermine his government and risk the return of the military to politics.

For regional governments, the big concern is centred on the hints that Mr Duterte has made with regard to his foreign policy, particularly in the country's dealings with China.

The Philippines is locked in a bitter territorial dispute with China over overlapping claims in the South China Sea.

The Aquino administration has taken a hardline approach towards the issue.

Mr Duterte is threatening to change tack and open direct negotiations with China, a move that would upend years of painstaking diplomacy by Asean.

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