Jakarta – A senior minister who teamed up with President Megawati Sukarnoputri's main rival said yesterday he was optimistic they could make a strong showing in the July polls for president and vice-president.

"We are certain that we are strong, at least we can go into the final" round of voting, said Welfare Minister Jusuf Kalla, who announced at the weekend that he would be Mr Susilo Bambang Yudhoyono's running mate.

The news is another blow to Ms Megawati's hopes of keeping her job in the July 5 polls after her ruling Indonesian Democratic Party of Struggle (PDI-P) performed poorly in the April 5 legislative elections.

A second round of voting will be held on September 20 if no one wins more than 50 per cent on July 5 in the country's first direct presidential election.

Ms Megawati, who had been courting Mr Jusuf as a running mate, is now likely to invite Vice-President Hamzah Haz to join her re-election bid, according to PDI-P executive Roy Janis, quoted by the Jakarta Post.

Mr Hamzah, who heads the main Muslim party, the United Development Party, said he expected to hear from her later this week. He said she had met him about four months ago to sound him out about possible future cooperation.

Mr Jusuf has a strong Islamic background. The businessman, who comes from Sulawesi, is also able to attract votes from the eastern islands to complement Mr Bambang's Javanese background.

"I think they are the best pair and also the pair with the strongest chances of winning," said politics lecturer Amir Santoso from the University of Indonesia. "Leave their political affiliation behind. The presidential election is a question of figures, not parties."