Spain is holding a referendum Sunday on the European Constitution - the first country in the bloc to do so.
Both of Spain's major parties are calling for a "yes" vote but the expected low turnout could get the landmark document off to a sluggish start and put the entire European project in jeopardy.
Voters will also go to the polls today in three European elections.
Surveys show Portugal's opposition Socialist Party easily defeating the ruling Social Democrats under current Prime Minister Pedro Santana Lopes.
Turkish Cypriot Prime Minister, Mehmet Ali Talat, who supports a United Nations plan for resolving the division of Cyprus, is expected to win a plurality in legislative elections.
Opinion polls in the northern German state of Schleswig-Holstein show a close race, but say voters are likely to return the center-left coalition to office.
Some information provided by AP.