Greek Cypriots will vote on Sunday in a parliamentary election that could threaten the unity of a governing coalition leading peace talks in Cyprus, discussions that are important for Turkey's EU bid, according to a report by Reuters.

Although the May 22 election has no direct effect on Greek Cyprus's presidential system of government, it is expected to shape alliances for the presidential contest in 2013, Reuters reported on its website.

Incumbent President Demetris Christofias rules in a coalition of his Communist AKEL party, and the centrist Democratic Party, or Diko, an uneasy alliance likely to come into sharper focus before the presidential vote. Polls predict Diko will keep its role of kingmaker, but may lose votes, possibly because of its affiliation with AKEL.

Polls give the main opposition party, the right-wing Democratic Rally, a marginal lead over AKEL with Diko in third place. "These elections are a first test and an opportunity for horse-trading with a view to the presidential elections," said Hubert Faustmann, associate professor of history and politics at Nicosia University. "Very often who supports whom in electing the speaker of parliament is a strong indicator of who will support whom in the presidential election."