Indonesia defence minister Prabowo Subianto declared victory in a presidential election on Wednesday after unofficial vote counts showed him with a huge lead that could see him win in a single round.

Political veteran Prabowo, a former special forces commander, had about 58 per cent of votes according to four pollsters, based on ballots counted in a sample of voting stations nationwide. The number of ballots tallied ranged from about 78 per cent to 93 per cent as of 1233 GMT.

In a rousing speech before supporters that drew huge applause, Subianto vowed to create a government consisting of “the best Indonesians” and said it was a victory for all of the people.

Rivals Anies Baswedan and Ganjar Pranowo trailed with about 25 per cent and 17 per cent respectively, according to independent pollsters conducting “quick counts”, which in previous elections have proven to be accurate.

A preliminary count by the election commission was far slower and showed Prabowo securing 57.7 per cent of votes with about 6 per cent of ballots recorded.

The contest pitted the two popular former governors against the pre-election frontrunner Subianto, who was feared in the 1990s as a top lieutenant of Indonesia’s late strongman ruler Suharto.

Crucially, Subianto has the tacit backing of the wildly popular incumbent Joko Widodo, who is betting on his former rival as a continuity candidate to preserve his legacy, including a role for his son Gibran Rakabuming Raka as the defence minister’s running mate.

Anies and Ganjar urged the public not to draw conclusions on the outcome and to await the official result, which is expected by March 20 at the latest.

The campaign teams of Ganjar and Anies said they were investigating reports of electoral violations, both calling it “structural, systematic and massive fraud”. They did not provide evidence.

Subianto is also a link to the brutal period of dictatorship that ended just over 25 years ago, when he served as a special forces commander in a unit linked to torture and disappearances, allegations Subianto denies.

Widodo’s successor will inherit an economy with impressive growth and ambitious infrastructure projects, including the ongoing transfer of the nation’s capital from congested Jakarta to the frontier island of Borneo at a staggering cost exceeding $30 billion.

The election also has high stakes for the US and China, since Indonesia has a huge domestic market, natural resources like nickel and palm oil, and diplomatic influence with its Southeast Asian neighbours.

Widodo’s rise from a slum to the presidency has shown the vibrancy of Indonesia’s democracy in a region rife with authoritarian regimes. But with a leading candidate linked to a former dictator, and Widodo’s son on the ballot, some observers fear that that democracy is eroding.