Greek Prime Minister George Papandreou won a crucial parliamentary vote of confidence for his new government Tuesday, making passage of controversial economic reforms more likely.

One hundred-55 lawmakers voted to back the new government while 143 voted against it. Two abstained. As expected, the vote was strictly along party lines. It came after a day of fierce debate, which saw several opposition members storm out of the chamber.

Thousands of Greeks massed outside parliament reacted with fury when the results were read. Riot police used tear gas to disperse a group of protestors who broke off from the main rally.

Mr. Papandreou is appealing to lawmakers to pass his package of spending cuts, tax hikes, and the sale of state assets. Passage would assure a $17 billion installment of last year’s $160 billion bailout from the European Union and International Monetary Fund.

Eurozone finance ministers have said they would approve the payment only when Greece passes more economic reforms.

Mr. Papandreou warned parliament that Greece would face bankruptcy and default next month if it fails to back his reforms and secure the loan payment.

The opposition and some members of the prime minister’s own Socialist Party say the reforms will not work. And millions of ordinary Greeks have been holding strikes and nationwide protests, angry that they are being asked to make more sacrifices.

Economic analysts say a default by Greece could spark another global financial disaster.