By Alkman Granitsas and Stelios Bouras, The Wall Street Journal

ATHENS–Greece's radical-left Syriza party was poised to win the country's European elections, official projections showed late Sunday, but failed to deliver a crippling blow to Greece's two-party coalition government.

According to the projections, Syriza, which opposes Greece's international bailout, was expected to win with 26.7% of the vote. That is roughly in line with its showing in national elections two years ago, and three to four percentage points ahead of its main rival, the center-right New Democracy party

But the governing coalition, made up of New Democracy and junior partner the socialist Pasok party, was buoyed by a stronger-than-expected performance by the socialists. Both parties were also poised to claim several symbolic victories in second round local elections that were also being held Sunday.

Greek voters headed to the polling booths, for the second time in a week, in a dual local and European election contest seen as a crucial test of confidence in the government of Prime Minister Antonis Samaras.

In a nationally televised address, Mr. Samaras said the voters had "sent a message to the government", but had otherwise failed to back Syriza's calls for a broad, popular revolt against the government.

This is the first time Greeks have been called to the ballots since the current two-party government came to power two years ago at the peak of the country's debt crisis. Since then, there have been tentative signs of a recovery in Greece's shattered economy, but they have yet to filter down to the ordinary voter or make a dent in the army of unemployed.

Public anger at the two governing parties, who took turns ruling Greece for much of the past 40 years, have helped fuel the rise of Syriza, as well as the extremist Golden Dawn party. The far right party looked poised to win 9% of the vote–better than its 7% showing in the last national polls–and ensuring it three seats in the European Parliament.

Voting at a polling station in the Athens neighborhood of Pangrati, Maria Skarpelou, 37, said she voted against Greece's two governing parties–and for the opposition–though without much conviction in her choice.

"I didn't actually want to vote for any of them," said Ms. Skarpelou. "But eventually I voted for Syriza. It's not that the leftists represent who I am, but at least we don't have hard evidence that they were stealing from us all those years."

But Syriza's efforts to turn the European elections into a referendum on the government that would sweep it from power failed to gain traction with voters. While New Democracy, projected to get 22.8% of the vote, was bruised, the losing margin was less than feared and the party looked set to win at least seven of Greece's 13 provincial seats.

Significantly, the socialists, running under the party logo Elia, or The Olive Tree, look set to win 8.1% of the vote, better than the 5% recent polls showed, while also winning the symbolically important race for Athens mayor.

"Syriza wanted this to be a referendum on whether the government should stay or go. The answer from the vote is: 'it should stay,'" said Theodore Couloumbis, professor emeritus at Athens University. "The winner of the European elections is clearly Syriza. But it's not enough of a margin of victory to justify throwing out the government." 

Greece's Syriza Party Leads in European Elections — 2nd Update