The 135 members of the National Council were elected in 48 single- and multi-memberconstituencies using a three-round system. Candidates had to receive a majority in the first or second round to be elected; if it went to a third round, only a plurality was required. Voters could cast as many votes as there were seats in their constituency. There was one seat for every 20,000 citizens, with seats allocated to cantons in proportion to their population.