That - based on the survey - about half of the Indonesian electorate has still not decided who to vote for implies that the outcome of the legislative as well as presidential race are far from clear, despite the nomination of Joko Widodo (the highly popular Governor of Jakarta) as the PDI-P's presidential candidate. This means that political parties can still win much votes through the political campaigns that are currently running.

According to the CSIS survey, the most popular political parties are the PDI-P (20.1 percent), Golkar (15.8 percent) and Gerindra (11.3 percent). The party of incumbent president Susilo Bambang Yudhoyono - Partai Demokrat (PD) - slid to 5.8 percent due to several corruption cases that emerged within the party's ranks in recent years. Possibly the most influential factor for supporting a party or presidential candidate is the 'corruption factor'. As Indonesian politics have for long been characterized by corruption, the electorate wants a leader who has a clean corruption record. This is one of the reasons why Joko Widodo has acquired such popularity among the Indonesian people as opposed to Aburizal Bakrie (presidential candidate of Golkar) and Prabowo Subianto (presidential candidate of Gerindra).

Further Reading:

PDI-P, Golkar and Gerindra are Most Popular Political Parties in Indonesia
Can Joko Widodo Accelerate the Democratization Process in Indonesia?
The Jokowi Effect: Indonesia's Financial Markets Gain on Political Certainty
Indonesia’s 2014 Presidential Candidates; a Profile of Aburizal Bakrie
Towards Indonesia's Presidential Elections: a Profile of Prabowo Subianto
The Tough Road of Yudhoyono's Democratic Party towards the 2014 Elections