ROME — Mario Monti, a former member of the European Commission, conditionally accepted a mandate on Sunday to form a new government in Italy whose main task will be to keep the country from being dragged under by Europe’s debt crisis.

Mr. Monti, 68, a respected economist who has promised to be a steady hand in a time of market turbulence, said he expected to move ahead as soon as he secured a parliamentary majority for the new government.

Assembling a majority usually requires days or weeks of talks, but Italy does not have the luxury of time. Skeptical investors have pushed the country’s borrowing costs to dangerous heights, putting at risk the euro currency that 17 nations share. The crisis forced the resignation of Prime Minister Silvio Berlusconi on Saturday, turning Italy’s most complex political shift in nearly two decades into one of its most urgent transitions.

President Giorgio Napolitano, who as the head of state must approve the formation of a new government, gave a tough speech on Sunday aimed at reassuring investors about Italy’s commitment to the euro and warning the nation’s insular political class about the stakes involved. He called on lawmakers to form a broad coalition in support of Mr. Monti that would be able to push through urgent economic measures.