Germans punished Chancellor Angela Merkel's centre-right coalition in a state election today, depriving her of a majority in parliament's upper house after she angered many by agreeing to aid Greece.
The loss in the state of North Rhine-Westphalia (NRW) is a blow to Ms Merkel little more than six months into her second term in office and means she will have to rely on opposition parties to deliver her policy agenda, which includes tax cuts.
An exit poll by ARD television put Ms Merkel's Christian Democrats (CDU) on 34.5 per cent and their Free Democrat (FDP) allies on 6.5 per cent, short of a majority and leaving the make up of North Rhine-Westphalia's next government unclear.
Exit polls are usually a reliable indication of the result. Result-based projections will start to come in during the evening and a final result is due during the night.
The election was widely regarded as a referendum on ms Merkel's government and came just two days after her coalition voted in parliament to release billions of euros in aid to debt-stricken Greece - a move deeply unpopular with the public.
Ms Merkel has also faced criticism from opposition parties for her handling of the Greece crisis after she initially resisted granting aid due to massive popular opposition to a bailout.
After finally backing a Greek rescue package, Ms Merkel said last week the plan must succeed or other European countries may suffer the same fate. She has also criticised financial market speculators for exaggerating tensions in the euro zone.
The CDU and FDP had ruled in NRW since 2005 and their coalition there mirrored a power-sharing deal at federal level.
There are some 13.5 million eligible voters in North Rhine-Westphalia and its economy is roughly the same size as those of Poland and the Czech Republic combined.
Five years ago, a defeat in NRW led then-chancellor Gerhard Schroeder to call an early election, which he lost to ms Merkel.
No one was expecting anything that dramatic this time around. But the defeat for CDU state premier Juergen Ruettgers may signal a turning in the political tide in Germany, which has been shifting in favour of the CDU for much of the past decade.
The ARD exit poll showed the Greens as the big winner, gaining 6.3 percentage points to 12.5 per cent. The Social Democrats (SPD), Germany's biggest opposition party, polled 34.5 per cent - the same as the CDU.
The socialist Left Party took 6 per cent of the vote.