IT is difficult to envision an American parallel to Syriza, the far-left political coalition that has a chance to throw Europe into further turmoil with a victory in this weekend’s Greek elections. But imagine a movement that combines elements from Occupy Wall Street and Ralph Nader’s 2000 presidential campaign, and you have a sense of where Greece’s leading opposition party would fit in the American political spectrum.

The party’s full name translates as Coalition of the Radical Left, which sounds like something that Glenn Beck might have scrawled on his blackboard during the health care debates of 2009 but actually describes the party’s supporters pretty accurately. Syriza is led by a former member of Greece’s Communist Party, and its constituents range from socialists to Trotskyists to groups with beyond-parody names like the Renewing Communist Ecological Left.

Greece is more hospitable to radical politics than the United States, but when Syriza was founded in 2004, it was strictly marginal. It took 3.3 percent of the vote in Greece’s legislative elections that year, while the country’s mainstream center-right and center-left parties won 86 percent of the vote between them.

But that was before the financial crash knocked over Greece’s fiscal house of cards and made its entry in the European Union’s common currency look like one of recent history’s gravest blunders. Today the Greek unemployment rate is 22 percent, the youth unemployment rate is over 50 percent, and the country has no political mainstream anymore. In last month’s legislative elections, the center-right party took 19 percent of the vote, the collapsing center-left party took 13 percent — and sandwiched in between them was Syriza, with as strong a claim to legitimacy as either.