An estimated quarter of a million people took to the streets in Germany on Saturday to protest against nuclear power.
Marches took place in Hamburg, Cologne, Munich and the capital Berlin ahead of the vote in wealthy Baden-Wuerttemberg state, at which nuclear energy is set to be a key issue.
Organisers says they marched under the banner "Fukushima Means: No More Nuclear Power Stations", referring to the nuclear plant in Japan which was damaged in the earthquake and tsunami on 11 March.
In light of the nuclear crisis in Japan, Chancellor Angela Merkel has ordered a three-month moratorium on extending the lifetimes of the 17 reactors in Germany and to shut off the oldest seven temporarily, pending safety checks.
Despite her protests to the contrary, voters believe she was electioneering.
An election is to be held on Sunday in Baden-Wuerttemberg state where nuclear energy is a key issue.
The CDU party has held power there for 58 years.
