The federal legislature in Germany has a one chamber parliament—the Bundestag (Federal Diet); the Bundesrat (Federal Council) represents the regions and is not considered a chamber as its members are not elected. The Bundestag is elected using a mixed member proportional system. The Bundestag has 598 nominal members, elected for a four-year term. Half, 299 members, are elected in single-member constituencies by first-past-the-post voting, while a further 299 members are allocated from party lists to achieve a proportional distribution in the legislature, conducted according to a form of proportional representation called the Mixed member proportional representation system (MMP). Voters vote once for a constituency representative, and a second time for a party, and the lists are used to make the party balances match the distribution of second votes. Overhang seats may add to the nominal number of 598 members: for example, in the 2009 federal election there were 24 overhang seats, giving a total of 622 seats. This is caused by larger parties winning additional single-member constituencies above the totals determined by their proportional party vote.