German chancellor Angela Merkel’s conservatives suffered a bitter defeat in Sunday’s state election in Lower Saxony, falling one seat short of a majority in coalition with the liberal party.

Opposition Social Democrats, who have dropped far behind the ruling party in nationwide surveys for this fall’s election, secured a slim majority with their Green party allies, enabling them to claim the prime ministership in the northwestern agricultural and manufacturing state that borders the Netherlands.

The left also regains a majority in the Bundesrat as a result of the vote, the upper chamber of the German parliament, meaning the opposition can block legislation’s from Merkel’s incumbent right-wing government and initiate laws itself.

That will not change if the conservative-liberal coalition holds on to power later this year, raising the likelihood of a “grand coalition” between Christian and Social Democrats, although the latter will be less tempted to join such a government if present poll numbers bear out. Whereas they stood at 30 percent as recently as October of last year, recent surveys have the party down to 23 percent support. Merkel’s conservatives, by contrast, are up to 43 percent but their liberal allies are struggling to cross the 5 percent election threshold.

Preelection polls in Lower Saxony didn’t give the liberals much chance of entering the regional parliament, however they surprisingly won almost 10 percent of the votes.

Christian Democrat leader and prime ministerial candidate David McAllister, who is a protégé of Merkel’s and mentioned as her possible successor, had encouraged right-wing voters to come out in support of the liberals to enable him to continue his government with them. It seems more conservative voters followed his advice than he bargained for. The Christian Democrats dropped 6.5 percentage points in the poll compared to four years ago with the difference going to the liberal party.

Neither the liberals’ nor the Social Democrats’ strong performance in Lower Saxony reflects national trends. The only party that came out an undisputed winner from Sunday’s election was the Greens who got almost 14 percent of the votes. They are reluctant to consider a coalition with the conservatives at the federal level, however, but it seems they won’t be able to rely on a big enough Social Democrat Party to form a left-wing majority government.