The legislative branch is made up of the Congress of Deputies (''Congreso de los Diputados''), a lower house with 350 members, elected by popular vote on block lists by proportional representation to serve four-year terms, and the Senate (''Senado''), an upper house with 259 seats of which 208 are directly elected by popular vote, using a limited voting method, and the other 51 appointed by the regional legislatures to also serve four-year terms.