Salim Osman – Indonesia's largest Islamic party, the Prosperous Justice Party (PKS), is defying predictions of tough times ahead of legislative elections due next April.

The results of two regional elections in West Java and North Sumatra earlier this month saw its incumbent governors Ahmad Heryawan and Gatot Pujo Nugroho, respectively, defeat their challengers from large parties.

The wins were sweet, coming after party chairman Luthfi Hasan Ishaaq was arrested on Jan 30 for allegedly receiving 1 billion rupiah (US$103,000) in bribes from meat importer PT Indoguna Utama to secure a government contract.

But the graft case will remain in public memory, with consequences. First of all is the PKS' credibility as an Islamic party that takes an anti-corruption stance, as well as its credentials of growing out of an Islamic movement.

"The public will now think of the PKS as hypocritical and that behind their sanctimonious facade, PKS politicians are just the same as any other politician from any other party," writes political analyst Burhanuddin Muhtadi of the Syarif Hidayatullah Islamic University in a commentary.

Secondly, its prospect of moving up the ranks from the fourth largest party in Parliament (DPR), to third place in next year's polls is in doubt. The party should not expect to do better than its performance in 2004 when it won 7.34 percent of the popular vote compared to only 1.4 percent garnered by its predecessor, the Justice Party (PK), in 1999.

That success was due to its anti-corruption stance and championing of good governance. For strategic reasons, it downplayed its Islamic agenda.

The PKS can forget about fielding its own candidates to contest the presidential election because next July is still not a good time for it to take a shot at the top job. It neither has a candidate of stature nor does it have the qualification to field one; the party may be unable to garner 25 percent of the national vote or seek partners whose combined votes meet the threshold in order to contest.

The third consequence is the "trust deficit" – party workers who saw their leaders as both trustworthy and having integrity will be demoralized.

Will the scandal, dubbed the Luthfi Affair, cause it to be eclipsed by other Islamic parties or even spell its end The setback is serious but is unlikely to cause its demise. Neither will it result in PKS being overtaken by rivals which face a grim future themselves in the face of changes in voter behaviour and competition from secular-nationalist parties.

The PKS remains a respectable organisation with a solid support base. It can count on loyal cadres and members likely to believe in the party's cause.This month's regional victories have shown that the party remains strong.

The PKS is not alone in being tainted by graft. Politicians from established parties like Golkar, the Indonesian Democratic Party – Struggle (PDI-P) and even the Democrat Party of President Susilo Bambang Yudhoyono have been convicted of corruption.

Likewise, the PKS, being the least corrupt, will not be doomed. The party's rank and file remain corruption-free and committed to anti-corruption principles.

The PKS embodies the compatibility of Islam and democracy in a Muslim-majority country. It began as an Islamic movement, the Jamaah Tarbiyah, active in university campuses. It became a political party, the Justice Party (or Partai Keadilan), in July 1998. It has since revamped into a progressive Islamic party that is open to all Indonesians irrespective of religion.

It has the right stance, being anti-corruption and supporting good governance while remaining engaged in issues affecting Muslims and Islam.

The PKS is part of the six-party coalition led by the Democrat Party of President Yudhoyono since 2004. The inclusion of the PKS provides the ruling coalition with balance in an otherwise secular-nationalist bloc. It is also a vital link to the Muslim ground.

In short, the corruption case will dent the party's credibility but will not lead to its demise. But it is imperative for its leaders to do some soul searching and to act to rebuild its tattered image.

One way for the PKS to distinguish itself is to come down hard on corruption, and to send a strong message that the party abhors corruption by even sacking those declared suspects in a corruption case or who are later found guilty of the offense.