After Greece, these elections will shake up Europe

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.

Greecehas 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:

France

Philippe Huguen | AFP | Getty Images

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."

U.K.

United Kingdom Independence Party leader Nigel Farage
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United Kingdom Independence Party leader Nigel Farage

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 MoreHas the economy already won the UK election?

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

Expected outcome: Too close to call. Latest opinion polls giving the opposition Labour Party a slight lead over Conservative Party, but with no absolute majority, the risk of a hung parliament is high.

Wild Card: The rise of smaller parties such as UKIP and the Scottish National Party is something to watch. The other risk is that of a second election held later in the year if either of the main parties fails to secure enough support or a minority government emerges.

Expert View: "The result is too close to call. This could make the formation of the next government a more drawn-out process than the markets are accustomed to, hurting business confidence in the short term," Credit Suisse said in a note. "The big medium-term risk for the U.K. economy is that the Conservative Party wins a clear mandate to hold a referendum on Brexit. Exit from the EU would be damaging to the U.K. economy."

Spain

Election: A general election is due by year-end with no date set yet.

Backdrop: Support for Spain's two dominant parties – the ruling conservative People's Party and the Socialists -- has hit record lows following a series of corruption scandals and harsh welfare cuts. This has boosted the popularity of the anti-austerity Podemos Party, which has gained ground in the past year.

Read MoreAs Podemos rises, will Spain become the next Greece?

Key election themes: Austerity, high unemployment, corruption.

Expected outcome: Latest opinion polls suggest the ruling People's Party would take 27.3 percent of the vote, followed by Podemos with 23.9 percent. With no clear majority, the major parties would be forced to form a coalition government, analysts say.

Wild Card: Podemos is the party to watch in this election with analysts drawing parallels in its rise with the success of the anti-austerity Syriza in Greece.

Expert View: "Podemos is a party that is very similar to Syriza and it is running very close in the polls against the ruling Conservatives and to where Syriza was polling in Greece a year or two ago," said Berenberg Senior Economist Christian Schulz. "So there is a risk Podemos could become the biggest party in this election. But Spain's electoral system is slightly different to Greece's and one party gaining 25 percent of the vote would mean it has to form a coalition."

Portugal

Election: General election expected in September or October

Backdrop: Portugal's centre-right coalition, elected in 2011, imposed painful austerity as part of its bailout. But the economy is growing again, helping Lisbon to last May exit the bailout. Unlike Greece and Spain, Portugal has not seen the rise of an anti-austerity party.

Key election themes: Still, the impact of austerity measures, economic reforms are expected to be key themes. Corruption scandals are also a source of discontent.

Expected outcome: A survey of voting intentions by Eurosondagem pollsters published in late February showed the coalition with 35 percent support, with centre-left Socialists, on 37.5 percent. This puts Portugal in the camp of elections this year that may be too close to call.

Wild Card: Whether the ruling coalition, made up of the Social Democrats and smaller rightest CDS-People's Party, run together or as two separate parties could determine the outcome of this election, analysts say.

Expert View: "Although the socialists are likely to win the elections, the outlook for government formation remains very uncertain," Antonio Roldan Mones, an analyst at Eurasia Group, said in a note. "This is because of a number of variables, the most important being whether the Social Democrats and the CDS-People's Party decide to run together or on separate lists. In the likely event they run on a single list, the election will be tight, but neither side will have an absolute majority."

Finland

Finnish Prime Minister Alexander Stubb
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Finnish Prime Minister Alexander Stubb

Election: Parliamentary elections set for April 19.

Backdrop: Finland has a coalition government led by centre-right Prime Minister Alexander Stubb. Its popularity has suffered as the economy struggles to recover from the global financial crisis. Finland's economic growth contracted 0.2 percent in the final quarter of 2014 from the previous year, while public debt has almost doubled since 2008. Despite dissatisfaction with austerity, all major parties are committed to the policy.

Key election themes:: The economy and austerity; the impact of Western sanctions on Russia and Moscow's retaliatory ban on meat and dairy imports from Europe. Russia is Finland's third biggest export market after Sweden and Germany. NATO membership could also be a theme.

Expected outcome: The opposition Centre Party, which has not held power for four years, is expected to win the most votes.

Wild Card: This general election follows the success of the anti-austerity Syriza party in Greece in January. What happens in Finland could provide a taster of what to expect in elsewhere in the region this year, analysts say.

Expert View: "Finland has become one of the most euro-sceptic countries since the anti-bailout Finns party won a fifth of the vote in the last parliamentary election," said Nicholas Spiro, managing director at Spiro Sovereign Strategy. "Premier Stubb has a tough race on his hands and is being forced to take an even more euro-sceptic stance."

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