Voters in the southern German state of Bavaria went to the polls Sunday in an election where Chancellor Angela Merkel's arch-conservative CSU allies were bracing for heavy losses.
The other partner in Merkel's fragile 'grand coalition', the Social Democrats, were also set to do poorly while the far-right and anti-immigration AfD looked certain to enter the state assembly.
The biggest winners, however, may be the left-leaning Greens who have doubled their poll ratings to 19 percent since the last state elections, which would make them the second strongest party.
Poll booths opened at 0600 GMT for 9.5 million eligible voters. Large numbers had said they were still undecided shortly before the vote, and first projections were expected from 1600 GMT.
If the polls prove correct, the Bavarian election will mark another step in the demise of 'big-tent' mainstream parties and the fragmentation of the political landscape, as seen in other western democracies.
For Merkel, now often labelled a lame duck leader in her fourth and final term, it would further raise political pressure two weeks ahead of another dangerous vote, in the central state of Hesse.
Parliamentary speaker Wolfgang Schaeuble, a veteran Merkel ally, has conceded that the two state polls will "affect national politics and thus the reputation of the chancellor," who seeks re-election as Christian Democrats (CDU) party chief in December.