ATHENS, Greece — A second round of talks to form a coalition government collapsed Wednesday, with Greece’s future in the euro and commitment to its international bailout deal in the balance and the specter of new elections looming ever larger.

Sunday’s election threw the country’s political scene into turmoil after voters angered by years of Europe’s harshest austerity program hammered mainstream politicians, but left no party with enough seats in Parliament to govern alone.

Alexis Tsipras, head of the runner-up Radical Left Coalition, met with heads of parties across the spectrum as he tried and failed to win support for Greece’s first left-wing-led government in four decades of democratic rule. Tsipras’ insistence that a new government denounce the bailout deal provoked a backlash from the other two main parties, who argued the move would see Greece leave the common European currency and endure years of poverty and isolation.