The Swiss Confederation, composed of 26 cantons, has a republican federal Constitution. Originally promulgated in 1848, it was wholly revised in 1874 and again in 2000. Legislative power is held by the bicameral Federal Assembly: the Council of States, with 46 members, elected for three to four years, representing the cantons (of which 20 send two members each and six, known as 'half-cantons', are represented by one member each); and the National Council, with 200 members directly elected by universal adult suffrage for four years, on the basis of proportional representation. Executive power is held by the Federal Council, which has seven members elected for four years by a joint session of the Federal Assembly. The Assembly also elects one of the Federal Councillors to be President of the Confederation (head of state) for one year at a time.