JAKARTA (Reuters) - Indonesia s speaker of parliament, who was arrested last week over his alleged role in a $170 million graft case, has sent a letter from his cell to house leaders pleading to be allowed to keep his job while he fights the charges. Setya Novanto, who has denied wrongdoing, is being held for 20 days for questioning by Indonesia s Corruption Eradication Commission (KPK). He made the request in a letter handwritten in his holding cell that was released to the media late on Tuesday. The KPK is investigating state losses of about $170 million after allegations that sums ranging from $5,000 to $5.5 million, generated by marking up procurement costs for national electronic ID cards, were divided up among politicians in parliament.  I ask other parliament leaders to give me an opportunity to prove that I wasn t involved,  Novanto wrote.   And in the meantime do not organize an ethics council plenary session on the possibility of making me non-active either as parliament speaker or as a member of parliament.  Novanto, also chairman of Golkar, Indonesia s second-largest party and a partner in the ruling coalition, is one of the most senior politicians to be detained by the KPK, which is popular among Indonesians for targeting members of the establishment suspected of abuse of power.  His battle with the graft agency has gripped Indonesia, where newspapers have splashed the story on front pages and memes mocking him have circulated on social media. He has clung to power through several previous corruption cases and repeatedly missed summonses for questioning by the agency in recent months, saying he needed heart surgery. Novanto was named a suspect on Nov. 10 again after using a controversial legal maneuver to get earlier charges dropped last month. In another letter, addressed to Golkar, Novanto said  there has been no discussion of me temporarily or permanently stopping as chairman of Golkar . In that letter he nominated Idrus Marham to serve as acting chairman of the party. Novanto s lawyer, Fredrich Yunadi, told Reuters it was up to parliament and party officials to decide if he should keep his posts, but he was confident that his client would win his case.    We have strong proof (and) in every court we always win,  Yunadi said. Asked if he was concerned about the strength of evidence against Novanto, KPK spokesman Febri Diansyah said:  From the beginning the KPK has had strong evidence, and the two people we have put on trial already (in this case) have been found guilty even up to an appeal stage.  