Labor chairman Ehud Barak negotiated with the group of four Labor rebel MKs about leaving the party legally before MK Ophir Paz-Pines's departure dealt the rebellion a death blow, sources close to Barak and the rebels confirmed on Saturday night. Paz-Pines's resignation will take effect on Sunday at 4:10 p.m., 48 hours after he submitted it to Knesset Speaker Reuven Rivlin. He will automatically be replaced by the next name on the Labor Knesset candidates list, Jewish People Policy Planning Institute fellow Einat Wilf, who will be sworn in on Monday. Ministers and MKs in the party spoke over the weekend about multiple maneuvers that had been under way behind the scenes over the past few months. Barak appointed his allies, Agriculture Minister Shalom Simhon and former minister Shimon Sheetrit, to negotiate an agreement with MKs Amir Peretz and Yuli Tamir that would have allowed Peretz, Tamir, Paz-Pines and Eitan Cabel to leave the party despite not having the fifth MK who would have constituted a third of the faction. At Barak's request, the talks broke down a few weeks ago when reports about a potential split in Kadima were first leaked. Barak had wanted to see whether several Kadima MKs would defect to Labor before proceeding with the talks. A source among the rebels said Barak was prepared to let the four MKs leave on their own because he was afraid that if MK Daniel Ben-Simon would join them, other legislators might also jump ship. The source said they were given the impression that Ben-Simon would have exercised his threat to facilitate the split at the conclusion of a three-month ultimatum demanding a start to the peace process, which he delivered on November 8. The four rebels hoped that if Ben-Simon would depart with them, Welfare and Social Services Minister Isaac Herzog would join them at a later stage. They considered then forming a left-wing confederation with Meretz. A rebel MK criticized Paz-Pines for not waiting with his departure until Ben-Simon's ultimatum expired, but sources close to Paz-Pines said he was tired of waiting and he did not believe Ben-Simon would carry out his threat. Ben-Simon said he could not confirm or deny reports that a split in the party would have happened in a matter of weeks had Paz-Pines stayed. He reiterated his threat to recommend leaving the coalition if diplomatic negotiations do not get off the ground. "If the peace process does not begin, we need to take Labor out of the coalition," Ben-Simon told Israel Radio on Friday. "We can't stay in a coalition that will not lead anywhere."