Both Prime Minister and Likud leader Benjamin Netanyahu and Labor chairman Avi Gabbay will attempt to gain new powers in their parties in meetings of their party secretariats that will convene on Thursday evening.Netanyahu’s allies will try to pass a proposal in the Likud secretariat to approve his confidant Tzuri Siso as the director-general of the party.Netanyahu appointed Siso as interim director-general in December, replacing veteran Gadi Arieli, who held the post for a decade.Siso’s appointment was seen as controversial due to his closeness to the Netanyahu family and his lack of managerial experience. Netanyahu decided then to appoint Siso interim director-general, because giving him the post permanently required a vote in Likud institutions that the prime minister did not know if he could pass.Following Netanyahu’s successful rally at the Tel Aviv Fairgrounds two weeks ago in which he entrenched his power in the party, he is not expected to have a problem passing the appointment of Siso, who has impressed party workers with his skills and his affable personality.Transportation Minister Israel Katz, who chairs the secretariat, initially opposed the Siso appointment.But he is expected to vote in favor on Thursday night. Meanwhile, in Labor, Gabbay’s plan to expand his power at the expense of party secretary-general Eren Hermoni will face its first test when the secretariat of Labor’s executive committee meets on Thursday night.Opponents of the move had their say at a meeting of the secretariat on Tuesday. Gabbay will formally present it and bring it a vote on Thursday after the party’s law committee prepared the proposal at a meeting on Wednesday.The most controversial change Gabbay intends to request is the right to select four candidates in realistic slots for the next Knesset, two of who would be placed in the top 10 on the party’s candidates list. He also wants to make decisions about committee appointments of Zionist Union MKs in the Knesset and gain more control over the party’s finances.As of Wednesday, no MK came out against Gabbay’s proposal. But that could change on Thursday, when his rival, MK Amir Peretz, will meet with Gabbay and reveal what he thinks about the plan for the first time.Both Gabbay and former prime minister Ehud Barak have denied reports that the plan is intended to facilitate a political comeback for Barak.