"I call on you to fall in line and vote for this difficult and painful deal that will help (the country) stand on its feet. Whoever has a conscience problem can resign," Papandreou told his lawmakers.
Together, the socialists and the conservatives have 236 deputies in the 300-member parliament.
Parliament will vote Sunday on emergency legislation approving the new bailout and a debt-swapping deal with private creditors. Further legislation detailing the measures demanded by, and agreed with, Greece's public creditors, the EU and the IMF, will be up for vote a few days later. The exact time has not yet been set.
Samaras also called for an immediate election once the bond swap deal with Greece's private creditors is over, saying he would not agree to the extension of the mandate of the coalition government beyond that date. Elections are normally due in October 2013. The bond swap deal with Greece's private creditors is expected to help Greece get rid of some euro100 billion of its debt. The bond swap must be completed before March 20, the redemption date for euro14.5 billion worth of bonds. Elections could then be held about three weeks later than that, at the earliest.
While the two parties met, union leaders staged a demonstration outside Parliament that attracted about 4,000 protesters, while up to 6,000 policemen patrolled the streets of Athens. The protest ended with some scuffles that left two people injured when police tried to clear the street in front of Parliament. Authorities are bracing for a much larger, and possibly violent, one on Sunday evening.
Another 4,000 turned out for a peaceful demonstration in Thessaloniki, Greece's second-largest city.
Costas Kantouris in Thessaloniki and Geir Moulson in Berlin contributed to this report.
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