While promising to curb corruption, which has hamstrung Tanzania for decades, Mr Mkapa's administration has noticeably failed to land any big fish.
Benjamin Mkapa
President Mkapa is running for a second term for the Chama Cha Mapinduzi, the former ruling party under the one party system. A former journalist, he came to power as 'Mr Clean', and this reputation has been kept largely intact despite allegations against some of his colleagues.
While promising to curb corruption, which has hamstrung Tanzania for decades, Mr Mkapa's administration has noticeably failed to land any big fish.
CCM's other main election platforms are the country¿s stability and the much-reformed economy, which has been performing very well.
Mr Mkapa must take much of the credit as the driving force behind Tanzania's extensive economic liberalisation, which has delighted the IMF and World Bank. Mr Mkapa is runaway favourite for president.
Augustine Mrema
Augustine Mrema is standing for president on the Tanzania Labour Party ticket.
Formerly deputy prime minister under CCM, he was removed and went to lead NCCR-Maguezi, an opposition party he has since abandoned.
He polled nearly 30% of the vote for president in 1995, and his blistering attacks on the government mean he is still a great crowd-puller.
His platform is anti-corruption, but little else is discernible. Mr Mrema appears to be tiring, and this may be his last roll of the political dice.
Ibrahim Lipumba
Professor Lipumba is the chairman of the Civic United Front, and their candidate for president. An economist, he spent a couple of years as economic advisor to Yoweri Museveni in Uganda.
CUF is starting to make inroads on the mainland away from its traditional support on the coast, but has a long way to go to catch CCM.
Earlier in the campaign Mr Lipumba tried to build a political alliance to challenge CCM, but only one small party joined.
He seems philosophical about his chances at the polls this year.
The Zanzibar archipelago has a devolved parliament and its own presidency. These are also up for grabs on Sunday. The main players are:
Seif Shariff Hamad
Seif Hamad is standing for the Zanzibari presidency for the Civic United Front.
He is another former CCM politician who fell out with the party and joined the opposition. Mr Hamad stood for the same post in 1995, and is believed by many to have won the vote.
CCM were declared the winners by less than 1%. This year's result on Zanzibar, and the manner in which it will come, is too close to call.
CUF is believed to have a moderate but significant lead over the ruling party, although no polls have been permitted on the isles.
Amani Karume
Mr Karume is the son of the assassinated first President of Zanzibar, Abeid Karume, and is standing for CCM. He is not a favourite of Salmin Amour, but was selected as a compromise with the party on the mainland.
He is seen by many as a conciliatory candidate, and may offer CUF a government of national unity, but the tone of his statements varies considerably.
Despite CUF's supposed lead, most Tanzanians expect Mr Karume to be the next president of Zanzibar.
Salmin Amour
Dr Amour is the incumbent at State House on Zanzibar, but he is stepping down at this election. This is not by choice - he attempted to alter the constitution to allow him a third term, but his party, CCM, blocked him.
They are, on the whole, relieved to see the back of a maverick politician who looked like settling in for a long stint in office.
Quite what Mr Amour will do after the election is not clear, as his power base has been eroded.
He still has plenty of friends in high places, but he may judge that Tanzania is not the place to retire.