The election result in Greece reflects a growing European backlash against austerity policies. Across the continent, support is growing for parties and groups outside the mainstream like Syriza, which triumphed in Greece on Sunday after pledging to renegotiate the country's huge bailout agreements.
Here are some of the groups to watch as they campaign for a change of course.
Many Spaniards are exasperated by government cutbacks amid recent economic misery and say the policies are partly to blame for a jobless rate close to 24 percent.
A leftist party called Podemos (We Can), created a year ago and led by pony-tailed political science professor Pablo Iglesias, is offering a new strategy. It proposes changing the way Spain's debt is paid off, nationalizing strategic sectors such as energy, and setting a maximum wage for all employees.
Spain holds a general election this year, with opinion polls indicating the party's support already equals that of the country's two mainstream parties.
Iglesias said Monday that Syriza's victory brings fresh hope. "The policies of unfair and ineffective cuts have been defeated by the Greek people," he said.
The Northern League party has seen its poll numbers rise in recent months as it draws support away from Italy's more mainstream center-right, including the Forza Italia party of ex-Premier Silvio Berlusconi.
Recent surveys have given the Northern League more than 12 percent of the vote, nearly double what the anti-immigrant and Euroskeptic party was polling at the time of the European Parliament elections.
The Lega, as it is known, derives its support from Italy's industrial north, which resents that so much of the tax it pays goes to Rome and the EU, while the underdeveloped south reaps the benefits. Party leader Matteo Salvini rejoiced at the Greek result, saying "it was a "beautiful slap in the face to the European Soviet Union of the euro, unemployment and banks." He added: "Now it's our turn!"
The Syriza victory could also give a boost to the anti-establishment 5 Star Movement.
The Portuguese have endured austerity measures under their center-right government since the debt-heavy country needed a 78 billion euros ($87.7 billion) international rescue in 2011.
Cuts in pay, pensions and public services, and steep tax increases were introduced in recent years to pay off national debt. Those measures have contributed to recession and 14-percent unemployment.
Small far-left parties such as the Portuguese Communist Party and the Left Bloc, and a handful of new civic groups including a Portuguese version of neighboring Spain's Podemos, are fighting those policies. But they have yet to gain national traction as Portugal prepares to hold a general election in the fall.
Most opposition to austerity is coalescing around the center-left Socialist Party, which has a strong lead in opinion polls.
The Greek election "is another sign of the political change that is happening in Europe, the failure of austerity and the need for new policies," Socialist leader Antonio Costa said.
After successfully exiting its own debt-driven bailout last year, six straight years of austerity in Ireland have driven hard-left opposition parties to unprecedented heights in opinion polls despite Ireland's post-bailout return to eurozone-leading growth.
Politicians from Ireland's two biggest left-wing voices, the nationalist Sinn Fein and the socialist Anti-Austerity Alliance, traveled to Athens to celebrate with Syriza and to call on Ireland's voters to deliver a similar breakthrough in a general election expected early next year.
Both backed Syriza's call for an EU-wide conference to negotiate restructuring and write-offs of national debt burdens for heavily-indebted eurozone countries.
"Syriza's victory is not just about Greece. It's about Ireland, Portugal, Spain and Italy too," said Pearse Doherty, finance spokesman for Sinn Fein, which in recent months has overtaken the government parties in opinion polls for the first time in the Republic of Ireland.
Marine Le Pen, head of the far-right National Front which among other things wants France to quit the eurozone, welcomed Syriza's victory which she said was "the opening of the trial of euro-austerity."
The National Front finished first in European Parliament elections last year, with 24.86 percent. According to the latest opinion polls, if France were to hold its presidential election today, Le Pen would lead in the first round — but lose in the second round. The French presidential election is set to be held 2017.
Though it is not represented in parliament, the populist party Alternative for Germany has had recent successes in state elections, and current polls put its growing support as high as around 10 percent.
The anti-euro currency group's spokesman Bernd Lucke blamed Greece's use of the euro for "driving the Greek voters into the arms of the radical-left party" Syriza, and said Greece should exit the shared currency.
Polls put the Freedom Party level, or even slightly ahead, of each of the parties in Austria's governing coalition — the Socialists and the centrist People's Party.
The Freedom Party opposes membership of the euro currency and wants to weaken the EU's centralized structure in favor of a loose union of national states.
The party's supporters include voters disillusioned by traditional parties, anti-foreigner rightists and the extreme-right fringe.
Dutch polls indicate that Geert Wilders' Freedom Party, currently holding just 12 seats in the 150-seat lower house of Dutch parliament, is now one of the Netherlands' biggest political movements, if not the biggest.
The party's populist policies include advocating that the Netherlands leave the European Union and dump the euro in favor of returning to the guilder.
AP reporters across Europe contributed to this report.