A senior minister in Indonesian President Megawati Sukarnoputri's government has teamed up with her main rival for the presidential election.
The results of the 5 April election are still being counted
Jusuf Kalla announced at the weekend that he would be Susilo Bambang Yudhoyono's running mate.
The move could be a further blow to Ms Megawati's chances of keeping her job after the 5 July presidential poll.
Her PDI-P party trails the Golkar opposition as counting continues for general elections earlier this month.
Millions of ballots are still to be counted, but it is already apparent that support for PDI-P (the Indonesian Democratic Party of Struggle) has dropped dramatically in favour of Golkar.
With two-thirds of the votes now counted, Golkar has secured 21.1% while PDI-P has 19.5 %.
This gap could widen further as more votes are counted from outlying regions, where Golkar is traditionally strong.
Mr Yudhoyono said he chose Jusuf Kalla as his running mate because he was a respected political figure whose vision for the country's future matched his own.
"We have the same commitment and ideas on how to
establish a more effective government that can settle the
problems facing the country in the next five years," Mr Yudhoyono said.
5 April - Legislative polls, contested by 24 parties
July - Presidential poll, contested by parties that win at least 3% of seats in legislative polls
September - Possible run-off if no-one wins 50% of total and 20% of votes in at least half the provinces
committed to establishing a solid government that is strong
and honest," Mr Kalla added.
According to an opinion poll last week, Mr Yudhoyono and Mr Kalla
were the most popular candidates for president and vice-president
Ms Megawati had herself been considering Jusuf Kalla as a running mate. She
is now likely to invite either her current Vice-President, Hamzah Haz, or Hashim
Muzadi, chairman of the country's largest Muslim group
Nahdlatul Ulama, to join her re-election bid.
Mr Yudhoyono is running on the ticket of
the small Democrat Party.
But despite joining Mr Yudhoyono's presidential bid, Mr Kalla has said he will not give up his affiliation to the Golkar party.
While Golkar is likely to have a strong voice in parliament, due to its successes in the legislative elections, it looks unlikely to provide a strong presidential candidate.
Its possible contenders are running well behind both Mr Yudhoyono and Ms Megawati in recent opinion polls.