The liberal ex-general commonly known as SBY is usually criticised for being too cautious, so his declaration on Sunday - so early in the election buildup - took many by surprise and prompted speculation about his motives.

'Yudhoyono is indecisive, weak and very slow to make political decisions but now we see that he is trying very hard to improve his image,' said Bima Arya Sugiarto of Paramadina university in Jakarta.

Mr Yudhoyono's early endorsement of Vice President Jusuf Kalla as his running mate was also breathtaking by his standards.

The two men have often been at loggerheads since they joined forces to win the 2004 polls, and some members of Kalla's powerful Golkar party want him to make his own bid for the presidency.

Mr Yudhoyono has just completed a Ramadan tour of the archipelago and has started to appear on billboards and in television advertisements for his small Democratic Party, signs that his election campaign is already in full swing.

His party's fortunes in the April 9 general elections will be crucial for his chances in the presidential polls.

'He is now in a very critical situation... he has to secure his political vehicle,' Mr Sugiarto said.

By nominating Mr Kalla as his running mate, Mr Yudhoyono may also want to force the Golkar chairman's hand and end speculation about his rival ambitions for the presidency, analysts said.

They have formed one of the most successful political pairings in Indonesia since the fall of Suharto in 1998, overseeing consistent economic growth of around six per cent while dealing with natural disasters and Islamic militancy.

But their relationship has not been easy, with Mr Kalla always ready to remind Mr Yudhoyono that he would not exist politically without the support of Golkar, the country's largest party.

'SBY seems to be afraid that Mr Jusuf Kalla will run for president and he doesn't want to give him the choice,' said political scientist at the University of Indonesia, Bantarto Bandoro.

Reform Institute executive director Yudhi Latif said Mr Yudhoyono had alienated other potential allies by declaring his hand for Mr Kalla so early.

'The coalition of Golkar and the Democratic Party alone would not win Mr Yudhoyono/Mr Kalla an election... Don't be surprised if Mr Yudhoyono/Mr Kalla don't even make it to the runoff,' he was quoted as telling The Jakarta Post.

Mr Yudhoyono is still the favourite to win the 2009 polls but he is facing a resurgent threat from former president Megawati Sukarnoputri, whom he trounced in 2004.

Anger over the president's decision to hike fuel prices by about 30 per cent in May to offset the ballooning cost of multi-billion-dollar oil subsidies dented his sky-high popularity ratings and boosted Ms Megawati's.

With crude back around US$100 (S$143) a barrel and inflation settling down from its spike of around 12 per cent in June, Mr Yudhoyono can claim to have weathered the commodities price crisis, at least for the time being.

He is also keen to trumpet recent victories in his war on corruption, and the timing of his announcement on Sunday could have been linked to Indonesia's rise on the corruption perceptions index issued by Transparency International.

The world's most populous Muslim state was rated 126th out of 180 countries last week, compared to its miserable 143rd out of 179 countries last year.

But the election is 10 months away, and Mr Yudhoyono must still convince the public that he is capable of taking the tough decisions needed to make good on his promises of faster development and cleaner government, analysts said.

'Given the fact that there is so much unfinished business on his agenda, whatever he says, the public thinks it will amount to nothing,' University of Indonesia's Bandoro said. -- AFP