policies; for the purpose of national conferences, they are treated somewhat like provinces, with voting delegates and the power to nominate leadership candidates. Tripartite Alliance The ANC is recognised as the leader of a three-way alliance, known as the Tripartite Alliance, with the SACP and Congress of South African Trade Unions (COSATU). The alliance was formalised in mid-1990, after the ANC was unbanned, but has deeper historical roots: the SACP had worked closely with the ANC in exile, and COSATU had aligned itself with the Freedom Charter and Congress Alliance in 1987. The membership and leadership of the three organisations has traditionally overlapped significantly. The alliance constitutes a de facto electoral coalition: the SACP and COSATU do not contest in government elections, but field candidates through the ANC, hold senior positions in the ANC, and influence party policy. However, the SACP, in particular, has frequently threatened to field its own candidates, and in 2017 it did so for the first time, running against the ANC in by-elections in the Metsimaholo municipality, Free State. Electoral candidates Under South Africa's closed-list proportional representation electoral system, parties have immense power in selecting candidates for legislative bodies. The ANC's internal candidate selection process is overseen by so-called list committees and tends to involve a degree of broad democratic participation, especially at the local level, where ANC branches vote to nominate candidates for the local government elections. Between 2003 and 2008, the ANC also gained a significant number of members through the controversial floor crossing process, which occurred especially at the local level. The leaders of the executive in each sphere of government – the president, the provincial premiers, and the mayors – are indirectly elected after each election. In practice, the selection of ANC candidates for these positions is highly centralised, with the ANC caucus voting together to elect a pre-decided candidate. Although the ANC does not always announce whom its caucuses intend to elect, the National Assembly has thus far always elected the ANC president as the national president. Cadre deployment The ANC has adhered to a formal policy of cadre deployment since 1985. In the post-apartheid era, the policy includes but is not exhausted by selection of candidates for elections and government positions: it also entails that the central organisation "deploys" ANC members to various other strategic positions in the party, state, and economy. Ideology and policies The ANC prides itself on