After Greece, these elections will shake up Europe
After Greece, these elections will shake up Europe · CNBC

Europe's voters head to the polls this year against a backdrop of rising populism, worries about Russia's renewed aggression and dissatisfaction with austerity.

Greece has already shaken things up, electing an anti-bailout left-wing government in January. Estonia's pro-NATO centre-right prime minister meanwhile declared victory in a weekend election, overshadowed by fears of interference from neighbouring Russia.

Elections are set to take place this year in France, Spain, Portugal, the U.K., Poland, Denmark and Finland. Here are some of the countries investors need to pay close attention to in the months ahead:

Election: Regional elections scheduled to take place between March 22 and 29.

Backdrop: France's economic growth barely made it into positive territory in the final quarter of last year and the government has faced opposition to its plans for long-term structural reforms that would lift the outlook for the euro zone's second biggest economy. The country is still reeling from the Charlie Hebdo massacre in January, putting some focus on immigration.

Key election themes: A weak economy and high unemployment, running just above 10 percent, labor market reforms. Immigration is also a key theme amid growing support for the far-right National Front .

Expected outcome: Latest opinion polls give the National Front up to 33 percent of national support. That puts it well ahead of the ruling Socialists and the opposition UMP of former president Nicolas Sarkozy .

The wild card: The success of the anti-immigrant National Front will be watched closely, since these regional elections could provide a taster of the presidential vote in two years' time.

Expert View: "This is an important election as it provides further information on whether the government can push ahead with reforms," said Martin Lueck, European Economist, at UBS. "It's also an important gauge of the 2017 presidential vote and any indications that the National Front is gaining popularity would be a blow to the reform process."

Election: General election set for May 7.

Backdrop: The U.K. has had a coalition government led by the Conservative Party since 2010. While the economy is recovering, discontent about low wages, immigration and inequality means this election is likely to be closely fought. The U.K's mainstream parties face strong opposition from the rise of the U.K. Independence Party (UKIP), whose anti-immigration, anti-E.U stance has gained traction with voters.

Read More Has the economy already won the UK election?

Key election themes: The economy, immigration and Britain's membership of the European Union.