ATHENS—Greece's leadership struggled to restore political stability to the country and safeguard its membership in the euro zone, as global powers gathered in France looked for ways to halt the spiraling European debt crisis.

Greek Prime Minister George Papandreou on Thursday agreed to shelve a controversial plan for a referendum on Athens's latest financial bailout. The turnabout followed a tumultuous few days that thrust Greece to the brink of political chaos, forcing euro-zone leaders to contemplate the possibility that...