In many electoral systems, ideologically similar parties can benefit from merging together. In Germany’s two stage system, however, it helps for similar parties to be separate.
The electoral system in Germany, known as Mixed-Member Proportional Representation involves two stages. First is the constituency stage, where 299 Bundestag (the German House of Commons equivalent) members are elected in single member constituencies, in the same manner as UK general elections.
The second stage involves a second vote. Voters vote for a party and their candidate list, and the parties are distributed seats so that their total number of seats, including constituency seats, is as proportional to parties’ vote shares as possible. There are at least 299 of these list seats, but the number varies in order to make the result as proportional as possible. Parties which win less than 5% of the vote, win less than 3 constituency seats and don’t represent a national indigenous minority (Danes, Frisians and Sorbs) are entitled to no list seats.
Variants of Mixed-Member Proportional Representation are also used in Italy and the Scottish Parliament and Welsh Assembly elections, among others. Due to regional State Parliaments in Germany legislating on many local and regional issues, the need for local representatives in the Bundestag isn’t particularly important, and parties tend to get a similar vote share in both rounds. It is very unusual for a party to win one or two constituency seats with less than 5% of the vote, and no party representing a national minority currently runs in Federal elections. For these reasons, the constituency representatives in the Bundestag are arguably obsolete.
Due to the nature of the system, if the vote share in the list vote remains the same when a party wins more constituency seats, it is entitled to less list seats in order to maintain proportionality.
In 2013, the Social Democratic Party of Germany (SPD) won 58 of the 299 constituency seats. The party won 25.7% of the votes in the second round, which amounted to 30.5% of the votes for parties who obtained more than 5% of the vote. Consequently, they obtained 135 more seats in the list stage, ending up with 193 seats out of a total of 631- or 30.5% of the total seats.
However, what if SPD members had set up a party named the German Social Democrats (for example), which the SPD then endorsed in the list stage? The German Social Democrats would have no constituency seats, and thus would be entitled to around 30.5% of the total seats alone. Combined with the 58 seats for the SPD, the voting bloc would potentially win close to 40% of the seats.
This effect is known as collusion, and the two largest parties in Italy both employed this tactic in 2001. As a result, the electoral law was altered to prevent such a situation arising again. For the 2009 German Federal Election, a new law was introduced preventing a party nominating an individual to be a candidate if they were a member of another party. Similarly, another rule exists to prevent the status of independent candidates being abused in a similar way, as effective vessels of a party to enable them to gain more representation than they merit. Thus, it appears at least that the loophole outlined above has been closed.
Consequently, such a strategy seems more hypothetical than a realistic idea. However, what if people were to vote for a genuinely distinct, but ideologically similar party in the second round? Die Grünen (The Greens) are a German party which, like the aforementioned SPD, are centre-left. On Sunday, they look set to meet the 5% threshold, but with one or even no constituency seats. If Green supporters vote for the SPD in the first stage, and SPD supporters vote for the Greens in the second, then it will lead to a significant electoral advantage to the centre-left, albeit not without damaging the proportional nature of the system.
In Albania, there are two large parties, and several much smaller ‘satellite’ parties, generally allied with one of the two larger ones. As a result, when Albania used a mixed-member proportional system, the two largest parties would win almost all of the constituency seats, but due to a large amount of the vote share going to the multiple smaller parties, they would seldom win list seats. Because of this, in the 2005 Albanian election, the two main parties explicitly endorsed smaller parties in the list stage. This led to just one party winning both list and constituency seats (only winning one of the latter), and Albania subsequently replaced the electoral system with a full list system.
The Mixed-Member Proportional electoral system has widespread support from many supporters of electoral reform, including in the UK, due to its proportional nature whilst still maintaining local representatives. However, it is evidently not without flaws.