Observers in Indonesia say that disorganization is threatening Monday's legislative elections. There are warnings that unsuccessful parties could use the expected disarray to challenge the results.

By some measures, Monday's vote is the largest single act of democratic choice in the world: 147 million voters casting 580 million ballots to choose among 500,000 candidates.

Few people believed the process would be trouble-free, but some observers are warning that the scale of problems that seems to be shaping up could provide losing parties with an excuse to reject the result.

Thousands of polling stations are still waiting to receive ballot papers and ballot boxes, many people say they have not received their voter registration cards, and there are worrying signs that not all electoral officials are certain about how to conduct the count.

Election officials have played down the magnitude of the problems, but Landry Subianto, an analyst with the Center for Strategic and International Studies in Jakarta, says the potential for trouble exists.

"I think these kind of technical [issues] will be used and exploited by those who are losing in the elections to really question the quality of the result, and also the legitimacy of the result," he said.

He says all parties are currently predicting that they will increase their share of seats, and he is worried that some of the large parties might hold street protests, if they end up with less than they expect.

According to a survey published on Monday by the respected U.S.-based International Federation for Election Systems, the current leadership could have some unpleasant surprises in store.

The ruling Indonesian Democratic Party of Struggle has been hoping to increase the 34 percent share of the vote it gained in the last elections. However, the survey shows that support for the party is declining, and it is only likely to receive 11.5 percent of the vote on Monday.

The survey, in common with other polls, shows that the main challenger, the Golkar Party, is in the lead, and is likely to receive more than 20 percent.

The survey also has some dispiriting news for the incumbent president, Megawati Sukarnoputri, who has long been the favorite in presidential elections scheduled for later this year.

According to the survey, Mrs. Megawati is currently polling only 11.6 percent. That is significantly behind her former security minister, Susilo Bambang Yudihono, who is currently leading in the survey with 18.4 percent.