In a process will run for another month, voting begins today in India, the world's largest democracy. Seventeen states go to the polls today; the rest vote progressively over the next three Thursdays and Wednesday 13 May. (The BBC has a handy map and guide.) There are 828,804 polling stations for the estimated 714 million eligible voters.

Prime Minister Manmohan Singh is leader of the Congress Party, which won a narrow surprise victory at the last election in 2004. Congress used to be unassailable, governing India for the first 30 years of independence, but has been in steady decline since then. A recent opinion poll put Congress and its allies in the lead but well short of an overall majority.