Indonesia’s main opposition won most votes at last month’s legislative elections but did worse than expected, final results have confirmed.

The Indonesian Democratic Party of Struggle (PDI-P) won 18.95 per cent of the vote, the election commission announced on Friday, in line with unofficial tallies released at the time of the April 9 vote.

The results, which were released just before a midnight deadline after an 11th-hour push to finish counting, also confirmed President Susilo Bambang Yudhoyono’s corruption-mired Democratic Party saw its support halve to about 10 per cent.

While the results put the PDI-P in first place, the party did considerably worse than surveys predicted before the vote, meaning their popular presidential candidate, Jakarta governor Joko Widodo, faces a tougher path to become head of state.

A party, or coalition of parties, needs 25 per cent of the national vote or 20 per cent of seats in the lower house of parliament to field a presidential candidate.

The results mean the PDI-P will likely have to form a larger-than-expected coalition to ensure enough support at the July election.

The election commission will announce the number of seats that each party won in the coming days.

Intense negotiations have been taking place in recent weeks to build coalitions.

The NasDem party, which won 6.7 per cent of the vote, has already thrown its weight behind the PDI-P, and the National Awakening Party, which won nine per cent, has also reportedly announced its support for Widodo’s party.