Angela Merkel's coalition of Christian Democrats and liberal Free Democrats lost a state election in northern Germany on Sunday, a week ahead of a much bigger regional ballot further west.
The election, in the northern state of Schleswig-Holstein bordering Denmark, brought gains for the opposition Social Democrats (SPD) and losses for Merkel's CDU, while the Greens and newcomer Pirate party also fared well and the liberal FDP slumped.
The result sealed a miserable evening for Merkel, both at home and inEurope. France elected a president pledged to challenge the German leader on the central precepts of her eurozone crisis management strategy.
The Greek election threw up an uncertain and destabilising outcome likely to raise further questions about Greece's ability to comply with the stringent terms of two eurozone bailouts. Merkel's position in Europe has been weakened recently by the collapse of her allied government in the Netherlands. Last night she also lost her main European colleague, Nicolas Sarkozy.
The defeat in Schleswig-Holstein of the same coalition she heads at the German national level comes a week before a much bigger bellwether poll in the state of North Rhine-Westphalia. The SPD and the Greens are also tipped to do well there.
Merkel's CDU narrowly remained the biggest party in the northern state, while its coalition partner slumped by almost half to 8%. But that FDP result was seen as a success following a string of disastrous regional results that resulted in it being drummed out of state parliaments.
The main opposition SPD gained almost five points to come within one point of the Christian Democrats. The Greens also gained slightly to about 15% while the maverick Pirates took 8% of the vote, complicating the attempts starting today to construct a viable new coalition. The haggling could take a while, with the favourite options being a Social Democrat-led government with the Greens and a small party representing the Danish minority, or Merkel's CDU remaining in office in a "grand coalition" with the SPD.
The elections next Sunday in North Rhine-Westphalia, whose population of about 18 million is bigger than those of many European countries, will be a much more important test for Merkel.
On what was an extremely busy day for voters all across Europe, elections also opened for local authorities in about 900 towns in Italy. They continue on Monday and are seen as an early gauge of the popularity of the reformist, caretaker government of Mario Monti following the collapse of Silvio Berlusconi's discredited administration last November.
Outside the EU in the Balkans, presidential, parliamentary, and local elections were held in Serbia and produced conflicting results. The incumbent president, Boris Tadic, came out narrowly ahead of his more nationalist challenger, Tomislav Nikolic, in the key contest for the presidency, meaning that the two men will stage a run-off in a fortnight.
But in the parliamentary ballot, Nikolic's Progressive party beat Tadic's Democrats into second place, according to partial vote counts. The result appeared to leave the third-placed Socialists, party of the late war crimes suspect and president Slobodan Milosevic, as king-maker, with its leader, Ivica Dacic, tipped to be the new prime minister.
Despite worries about staging the elections in the breakaway country of Kosovo – Nato troops were reinforced and international election organisers dispatched – the balloting there passed off without much incident.
• This article was amended on 7 May 2012 to correct the population figure for North Rhine-Westphalia.