Athens (AFP) - Whatever the outcome of wrangling in Brussels over its debt problems, Greece may be heading for further political turmoil as defections by leftwingers weaken Prime Minister Alexis Tsipras' grip on government.Out of 149 lawmakers in his radical-left Syriza party, 17 refused to support him in Saturday's vote which authorised the government to reopen negotiations for a bailout in exchange for austerity measures.The revolt meant Tsipras could not count on his majority in the 300-seat assembly.He got the votes he needed with the backing of the right-wing opposition and a coalition that included Socialist and other left-wing legislators.Since the vote Greece has plunged back into tense talks with the 18 other members of the eurozone over a potential bailout to keep the heavily-indebted nation in the euro. But any deal will inevitably come tied to tough conditions, demanded especially by northern European countries.It will require the approval of the Greek parliament -- and Tsipras will again not likely be able to rely on the support of a portion of his party. Fifteen Syriza MPs who had backed Tsipras on Saturday sent a letter to the premier saying he should not count on them to approve any future reforms demanded by Greece's creditors. More austerity demands are expected as Germany's fiscal hawks faced off on Sunday against doves led by France at a summit of the 19 eurozone leaders in Brussels, with Athens facing demands to push through new reform laws as early as the coming week. - New elections? - Among radical politicians who have bucked supporting Tsipras are Energy Minister Panagiotis Lafazanis -- a sworn foe of the euro -- and parliamentary president Zoe Konstantopoulou, a thorn in Tsipras's side.Konstantopoulou has become an icon for the left with an oppositional stance against the country's creditors, including a parliamentary inquiry she launched that concluded Germany owed Greece 279 billion euros ($311 billion) in World War II reparations.According to Greek centre-right daily To Vima, Tsipras now finds himself stuck "between (German Finance Minister Wolfgang) Schaeuble, Zoe and Lafazanis."For the Greek press, Tsipras has just three options: new elections, a national unity government or a crackdown on Syriza members.He could invoke a code of conduct signed by party lawmakers which calls on them to hand over their votes to the party in case of policy disagreement with the government. Kathimerini daily wrote that Tsipras "made the right choice for the country, but he sacrificed his party.""The only solution is the formation of a new government capable of guaranteeing the country a future in Europe," it added.According to To Vima, the stance of the 32 rebel MPs "who are against any agreement with the creditors and who are engaging in blackmail" make it necessary to form a national unity government. Greek Economy Minister George Stathakis sent a warning to rebel Syriza members on Saturday."If an MP does not agree with the government's policies, he must obey the rules and, if it is a deep disagreement, renounce his seat," Stathakis said.Join the conversation about this story »