ELENA BECATOROSATHENS, Greece (AP) â¿¿ Greek conservative party head Antonis Samaras was sworn in as prime minister Wednesday at the helm of a three-party coalition that will uphold the country's international bailout commitments. The move ends a protracted political crisis that had cast grave doubt over Greece's future in Europe's joint currency and threatened to plunge the continent deeper into a financial crisis with global repercussions. But the new government still has massive challenges ahead: It must deliver on pledges by its predecessors to generate huge new savings, privatize publicly-owned companies and real estate, cut about 150,000 civil service jobs in coming years and open restricted professions to competition. Samaras, a U.S.-educated 61-year-old economist, was sworn in three days after his New Democracy party won the second national elections in six weeks but without enough votes to form a government on its own. He is Greece's fourth prime minister in eight months. German Chancellor Angela Merkel congratulated Samaras by phone and wished him "luck and success in the difficult work that lies ahead of him," the German government said. It added that Merkel hopes for "good cooperation" with Samaras and his government, and she invited him to visit Berlin. Germany is the main contributor to Greece's two multi-billion euro rescue loan packages. The conservatives will join forces with the socialist PASOK party, which is led by former finance minister Evangelos Venizelos and came in third place, and the smaller Democratic Left led by Fotis Kouvelis. Discussions on the line-up of ministers were expected to be completed by Wednesday night. "I will ask the new government that will be formed tomorrow to work hard so that we can offer tangible hope to our people," Samaras told reporters as he left the presidential mansion. Greek stocks rose marginally in response to the news, with Athens shares closing up 0.5 percent, limiting earlier gains.