After a decade in opposition, the Indonesian Democratic Party-Struggle (PDI-P) emerged as the clear leader in the nation's general election on Wednesday, scoring approximately 19 per cent of the vote share, according to a quick count of 90 per cent of the votes.
The showing will give former president Megawati Sukarnoputri's party a freer hand in nominating a running mate for its presidential candidate Joko Widodo for the July 9 presidential election.
"God be praised, PDI-P has been given the trust with the first in ranking," said Mr Joko at a press conference after 50 per cent of the votes had been counted in an unofficial tally known as quick count.
At 5pm local time, Golkar chief Aburizal Bakrie congratulated PDI-P as the winner of the legislative election, based on results when 70 per cent of the vote had been counted.
He later tweeted: "For the quick count results of the legislative elections that put PDI-P in the first place, and Golkar in the second, I congratulate PDI-P."
Golkar, the party of former president Suharto, retained its position as the second-largest force in the house with about 15 per cent of the vote while Greater Indonesia Movement Party (Gerindra) was the biggest gainer with about 12 per cent of the votes, up from only 4.5 per cent in the 2009 election five years ago.
This was enough to pip the Democratic Party of President Susilo Bambang Yudhoyono out of the top three rankings. His party scored about 10 per cent, less than half of the 20.8 per cent it received in 2009.
Also poised for a comeback is the National Awakening Party (PKB) of former president Abdurrahman Wahid, which has emerged as the leading Islamic party with about nine per cent of the vote.
PDI-P's result, however, is lower than the expected result of at least 25 per cent, and observers say it could be due to "overexposure" of Mr Joko, commonly known as Jokowi.
Mr Philips J Vermonte of the Centre for Strategic and International Studies (CSIS) said: "It is as if the PDI-P was lulled into pushing Jokowi to the front as a figure to gather the votes. What is clear is that other parties work harder to retain and get more votes."
Pollster Indikator Politik Indonesia analyst Burhanuddin Muhtadi added that PDI-P's TV advertisements were ineffective and negative sentiment rose against Mr Joko in the media.
Mr Joko told reporters on Wednesday that coalition talks may start as soon as Thursday, but added later that his party has been in daily discussions with the chiefs of other parties.
Analysts believe Golkar will play a defining role in negotiations for the presidential elections.
Mr Philips said: "Golkar has less ambition for the presidential race compared to the PDI-P and the Gerindra Party. But, the fact is, it has enough bargaining power to play a significant role. Therefore, whoever manages to ask Golkar to join them, will likely secure the presidential race," he said on Wednesday, The Jakarta Post reported.
Some 186 million eligible voters in Indonesia went to the polls to choose their representatives at four levels - MPs in the 560-seat national parliament, provincial assembly, district or city assembly, and the 132-seat regional representative council.
They voted at over 545,000 polling stations across the sprawling archipelago of 17,000 islands, from the highlands of Papua to islands off the coast of Aceh.
Over 200,000 candidates from 12 national parties are vying for a total of 19,699 seats.
The vote will also determine which parties will be able to put forth a pair of candidates for the July 9 presidential election.
Parties must obtain at least 20 per cent of the seats in the national Parliament, or 25 per cent of the popular vote.
The poll comes after 21 days of vigorous campaigning from parties and candidates, and three cooling-off days, which ended on Tuesday.
Counting commenced at 1.30pm local time, about half an hour after the polls closed. Indonesia has three time zones.
Although official final results will not be released until early May, quick count results give a fairly accurate indicator of how voters leaned.