Carlos Paath, Ponorogo – Jakarta Governor Joko Widodo has been enlisted by his party to campaign for its candidate in the upcoming East Java gubernatorial election, in what analysts are calling a questionable attempt to leech off his soaring popularity.

Joko took part in a campaign rally and a meet-and-greet with residents of Ponorogo district on Sunday, alongside Bambang Dwi Harsono, the candidate put forward by the Indonesian Democratic Party of Struggle (PDI-P) to contest on the Aug. 29 ballot in the province.

Speaking to reporters at Songgolangit Market, where he and Bambang met with traders and residents, Joko said he was convinced that Bambang would go on to defeat the other contestants, including Governor Soekarwo, and win the election.

"He's definitely going to win. I'm sure of it," he said. "Just you wait and see on the 29th. It's going to be a victory."

He also warned voters against falling for vote-buying tactics, echoing a theme being peddled prominently by the PDI-P as it sees its candidate lag in the opinion polls to Soekarwo and the main challenger, Khofifah Indar Parawansa.

"As we get closer to polling day, offers of money to voters will abound," Bambang said. "If anyone is found giving out sums of Rp 50,000 to Rp 100,000 [$4.80 to $9.60], they should be arrested immediately. We have to beware of this evil."

Among the other PDI-P stalwarts who took part in Bambang's campaign were Ganjar Pranowo, who won the Central Java gubernatorial election in May, and Rieke Diah Pitaloka, who narrowly lost out in the West Java ballot.

Joko also took part in Ganjar and Rieke's campaigns – a practice that party supporters say is meant to help the candidates benefit from Joko's widespread popularity, but one that poll observers say does not guarantee votes, as evident in the West Java election in February.

"In some contexts, it's pretty effective for the candidates to be associated with Joko," Rully Akbar, a researcher at the Indonesian Survey Circle (LSI), said in Jakarta on Sunday, as quoted by Detik.com.

"But to date there still hasn't been any research into whether the 'Jokowi effect' is real or not," he added, referring to Joko by his popular nickname.

Rully cited the PDI-P's losses in the West Java poll, as well as the Bali election in May and the North Sumatra ballot in March – in which Joko also campaigned on behalf of the party's candidates – as negating any perceived benefits to the candidates of having the popular Jakarta governor stump for them.

"The PDI-P hasn't won all of the regional elections in which they've involved Joko," Rully said. However, he predicted that Joko's presence would give Bambang's campaign a bit of a boost, given that the PDI-P's team on the ground was "sluggish."

"Whether anyone cares to admit it or not, the Jokowi effect can be very helpful. But how significant of a factor it will be has yet to be analyzed in greater depth," he said.

Meanwhile, a prominent cleric from the country's biggest Islamic organization has thrown his support behind Khofifah, who narrowly lost the vote and subsequent re-vote to Soekarwo in the 2008 election.

Hasyim Muzadi, the former chairman of Nahdlatul Ulama, said on Sunday that given that East Java was the NU's birthplace and stronghold, it was about time that the governor be someone affiliated with the organization.

Previous governors have traditionally partnered with an NU running mate to cater to the group's significant voter base. This includes Soekarwo, whose deputy, Saifullah Yusuf, is an NU member and has been engaged in a bitter spat with Khofifah over the NU endorsement.

Hasyim claimed there would be less corruption with an NU member leading the province, and urged voters not to underestimate Khofifah just because she was a woman.