Germany's state of Hamburg is electing a new parliament in what is a major test for Chancellor Angela Merkel's conservatives.
The latest polls before Sunday's election indicated her party appeared set to lose power there after 10 years, and a center-left coalition of Social Democrats and The Greens was on track to win a solid majority.
The northern port city used to be a Social Democratic stronghold in the past and opposition leader Olaf Scholz appears poised to replace conservative Mayor Christoph Ahlhaus.
The vote is the first of a series of seven such votes this year. Germany's 16 states wield wide power over national policy through their representation in parliament's upper house.
About 1.3 million people are eligible to vote in Hamburg.