The Liberal Democratic Party (LDP), which had a majority of 275, has lost 48 members who opposed the government in the no- confidence vote last month, and defected to rival parties. It is defending 227 seats, and is expected to win about 220, which would make it by far the largest party in the Diet, but without an absolute majority. Any new government would thus have to be a coalition, and the post-election period is likely to be chaotic until a deal is done.
The LDP is led by Prime Minister Kiichi Miyazawa, but with personal popularity ratings in single figures, his future looks unpromising. Alternative candidates for LDP leadership - and prime ministership if it forms a government - are Toshiki Kaifu, a former prime minister who has little power but a clean image, Ryutaro Hashimoto, a former finance minister, and Masaharu Gotoda, the current Justice Minister.
The two main opposition parties are new. The Shinsei (renewal) party has 36 incumbent members, all of whom split from the LDP, and is running 69 candidates; it is expected to win 40 to 50 seats.
The official leader is Tsutomu Hata, a former finance minister, but the real power is Ichiro Ozawa, a bright, aggressive politician who orchestrated the LDP split and wants to boost Japan's international role.
The Japan New Party was set up last year by Morihiro Hosokawa, and has been campaigning for decentralisation of power and corruption-free politics. It is expected to win about 40 seats, and could hold the balance of power between an LDP-dominated government and a Shinsei coalition of opposition parties.
The Socialists, led by Sadao Yamahana, have been the main opposition party until now. However, opinion polls show them losing support rapidly, and they will be lucky to hold on to half their 134 seats.
The remaining 100 seats will be split between the Komei party, set up by Buddhists, the Communists, two small left-wing splinter parties and a handful of independents.