Bingu wa Mutharika - United Democratic Front
Economist Bingu wa Mutharika was an early member of the UDF, but was best known for his six-year tenure as secretary-general of the Common Market for Eastern and Southern Africa (COMESA). However, when he formed the United Party in 1997, he lost his seat at COMESA. In Malawi's 1999 general elections, 70-year-old wa Mutharika polled last.
His political rehabilitation followed the blocking of outgoing president Bakili Muluzi's bid for a third term, and his selection as Muluzi's successor outraged several senior members of the party, who quit in protest.
In the current election campaign, the private media have pointed out Muluzi's earlier attacks on wa Mutharika, in which he made allegations of improper conduct at COMESA. Parallels have also been drawn with Zambia, where outgoing president Frederick Chiluba handpicked his successor, who turned on his benefactor when he assumed office.
Wa Mutharika has publicly declared his loyalty to Muluzi, who will hand over the presidency but retain control of the UDF. Wa Mutharika, a Roman Catholic, comes from Thyolo in the UDF's Southern Region stronghold.
Gwanda Chakuamba - Mgwirizano coalition
As head of the seven-party opposition Mgwirizano (Unity) alliance, Gwanda Chakuamba, the 69-year-old Republican Party leader, is expected to offer the most serious challenge to wa Mutharika and the UDF's hold on power. The alliance has won the support of Malawi's churches, but its inability to unite all the opposition parties is its Achilles heal.
In the 1999 elections, Chakuamba, then leader of the Malawi Congress Party (MCP), lost to Muluzi by 300,000 votes in a contest the opposition claimed was rigged, and declared: "If I was a young man, there could have been blood in this country."
A senior minister under the former dictator, Hastings Kamuzu Banda, and leader of the MCP's feared militia, the Malawi Young Pioneers, he was arrested in 1980 and sentenced to 22 years in prison for allegedly trying to assassinate Banda. He served 12 years and emerged a popular hero, then briefly joined the UDF before rejoining the MCP, and was chosen by Banda as his successor.
Chakuamba was born in Malawi's southernmost district of Nsanje in the Lower Shire Valley but, with the inclusion of the Mgode rebels - heirs to the anti-UDF political tradition of the Alliance for Democracy - in the Mgwirizano coalition, is also likely to pick up significant votes in the north of the country.
Brown Mpinganjira - National Democratic Alliance
Once seen as Muluzi's right-hand man, Brown Mpinganjira was one of the early members of the UDF when it was still an underground movement, but the 55-year-old politician has since turned into a notable adversary of the UDF.
A powerful senior minister, he was sacked by Muluzi in 2000 on corruption charges but never convicted, for reportedly showing presidential ambitions. Regarded as an astute and forceful character, Mpinganjira went on to launch his National Democratic Alliance, which in its early days was regularly harassed by the UDF's militants, the Young Democrats.
Mpinganjira, who hails from southern Malawi, has stayed out of the Mgwirizano coalition, preferring not to play second fiddle to its leader, Gwanda Chakuamba. He is expected to make a dent in the UDF's support in the south, and as the youngest presidential candidate, is believed to be preparing for a more effective challenge in 2009.
John Tembo - Malawi Congress Party
At 72, John Tembo is the oldest of the presidential candidates and carries the most political baggage from the Banda era. As part of Banda's inner circle, and uncle to Cecilia Kadzamira - Banda's "official hostess" - Tembo wielded great power and evoked fear.
He was reportedly part of an MCP National Executive Committee that resolved to kill the country's Catholic bishops in 1992 for issuing a pastoral letter calling for political reforms.
When Banda retired in 1994, Chakuamba rather than Tembo was chosen as his successor. After Banda died in 1997, Tembo used his wealth and political clout in the Central Region to unseat Chakuamba as party leader.
Justin Malewezi - Independent Candidate
Despite his membership of the ruling UDF and his position as Malawi's Vice President, Justin Malewezi announced on New Year's day 2004 that he was quitting the party to stand as an independent in the May elections, but refused to resign his office.
Malewezi initially joined the People's Progressive Movement (PPM) of former UDF heavyweight Aleke Banda, but when PPM joined the Mgwirizano coalition, he announced his decision to stand as an independent and launched a campaign based on issues and not character assassination.
Hailing from the Central Region, the quiet man of Malawian politics has preserved his dignity in the campaign, despite being insulted in public by Muluzi and the UDF.