Zweitstimme

Zweitstimme is the second vote in German federal elections, used to determine each party's share of seats in the Bundestag under Germany's mixed-member proportional representation system. Voters have two votes: the Erststimme for a direct candidate in their constituency, who wins that seat if they have the most votes; and the Zweitstimme for a political party's state list. The Zweitstimme largely decides how many seats each party receives in the Bundestag, independently of which candidates won constituencies.

The second vote is cast for a party rather than a person, and the party's nationwide proportion of Zweitstimmen, subject to the 5% threshold (or winning at least three direct mandates), determines its overall seat share. The state-level results feed into a nationwide seat allocation, typically using the Sainte-Laguë method. If a party wins more direct mandates through the Erststimme than its Zweitstimme would entitle it to, the result is Überhangmandate (overhang seats); to maintain proportionality, Ausgleichsmandate (leveling seats) are added for other parties.

The Zweitstimme thus enables proportional representation and multi-party participation in the Bundestag and allows voters to split their votes—supporting a preferred party with the second vote while voting for a specific candidate with the first vote. The total number of Bundestag seats can fluctuate because of overhang and leveling mandates.