Formal campaigning opened on Monday in Indonesia for elections to national, provincial and local legislatures in which 171m largely Muslim voters are expected to clear the way for the re-election of Susilo Bambang Yudhoyono as president.

Mr Yudhoyono is not a candidate in the April 9 legislative election, but candidates for the July 8 direct presidential election must be backed by parties that win 20 per cent of the 560 seats in parliament, or 25 per cent of the popular vote in what is the world’s third largest democracy.

After eight months of initial canvassing restricted largely to the media, Mr Yudhoyono’s Democrat party, with more than 20 per cent support, is leading the Indonesian Democratic Party of Struggle, led by Megawati Sukarnoputri, Mr Yudhoyono’s predecessor, which is registering support in the mid-teens.

A percentage point or so behind is Golkar, the political machine of the former dictator Suharto and the largest party in parliament. Islamic-oriented parties, which won more than a third of the vote at the last election in 2004, are now polling about half that level.

The wildcard is the new Great Indonesia Movement party led by Prabowo Subianto, a former Suharto son-in-law whose military career was cut short in 1998 after his involvement in the kidnapping of some two dozen activists, 13 of whom disappeared.

Up to a dozen parties are expected to pass the 2.5 per cent popular vote threshold required to win parliamentary seats.

Some 20 per cent of voters remain undecided, but analysts believe that a sizeable proportion of these will back the Democrat party because Mr Yudhoyono’s popularity and record are likely to decide the campaign in the absence of a meaningful policy debate.

According to Roy Morgan International, a market research company, he is one of only three democratically elected leaders whose job approval rating exceeds 60 per cent – the others being Barack Obama of the US and Australia’s Kevin Rudd.

In presidential election surveys Mr Yudhoyono, a taciturn former general known as SBY, is polling in the mid-40s and rising. He is at least 20 percentage points ahead of Mrs Megawati, with all other potential candidates in single digits.

Speculation is mounting that if the Democrat party does very well, securing more than 25 per cent of the parliamentary seats, Mr Yudhoyono could create enough momentum to win a majority in the first round of the presidential election in July and so avoid a September run-off between the top two candidates, which was required at the last election.

“The public perception of SBY is that he is doing a good job and so this will undoubtedly help the Democrat party,” said Sunny Tanuwidjaja of the Centre for Strategic and International Studies. “But the economic crisis will be the main factor . . . Will the stimulus limit the impact on people or not?”

Mr Yudhoyono has announced a Rp71,300bn ($5.9bn, €4.6bn, £4.2bn) package of tax cuts and infrastructure projects due to be rolled out later this month.

Indonesia’s three elections since the fall of Suharto in 1998 have been largely free and fair and observers are confident this one will be no different.

The only big change in the proportional representation multi-member constituency system that Indonesia uses is that voters will this time be allowed to select individual candidates, rather than simply nominating a party. This innovation is intended to remove from the parties the power to decide which candidates end up sitting in parliament.