BERLIN — Chancellor Angela Merkel of Germany faced the greatest crisis of her political career Monday, after late-night negotiations to form a new government collapsed, raising the prospect of a snap election. The chancellor expressed a preference for a new election, saying that she was doubtful that a government lacking a majority in parliament could handle the many challenges it faces. “I don’t want to say never, but I am very skeptical, and believe that new elections would be the better way forward,” the chancellor told the public broadcaster ARD. The rapid developments thrust Germany, a bedrock of stability in Europe, into its worst period of political uncertainty since the Cold War.