Parallel voting

Parallel voting describes a mixed electoral system where voters participate in an election or in effect, two elections (that are organizationally combined) whereby representatives are voted into a chamber using at least two different systems. Parallel voting, sometimes known as mixed member majoritarian (MMM), semi-proportional or supplementary member (SM) system, combines first-past-the-post voting (FPTP) with party-list proportional representation (PR). The system has been applied in the election of national parliaments as well as local governments in various places such as Japan, South Korea, Taiwan, Lithuania, Russia, Argentina and Mexico.

Parallel voting or MMM is distinct from another mixed election system known as mixed-member proportional representation (MMP), where a single election takes place, and the party vote determines what proportional share of seats each party will receive in the legislature, in order to "top up" its constituency seats.

While FPTP with PR is the most common pairing in parallel systems, any other combination is effectively possible. For example, in Italy and France, regional elections are held under a parallel system where a group of councillors are chosen by a party-list system, and the remaining part with a general ticket, so to ensure that a single list wins well over half the seats.