Ruairi Quinn
Age: 51 Place of birth: Dublin. Education: Blackrock College, UCD School of Architecture and Athens Centre of Ekistics.
Marital status: Divorced from his first wife, with whom he had a son and a daughter, he married Liz Allman in 1990. They have one son.
Political career: A member of Dublin City Council from 1974 to 1977, he was elected to the Dail in 1977 for Dublin South East, but lost his seat in June 1981, regaining it in February 1982. He was minister of state for housing and urban affairs in 1982-83, minister for labour (1983-87), spokesman on the environment (1987-89) and finance (1989-93), minister for enterprise and employment (1993-94) and minister for finance (1994-97). He has been Labour's deputy leader since 1989.
Career high point: Chairing the EU Council of Finance Ministers during Ireland's presidency in December 1996 when he helped to engineer a key agreement paving the way for the single currency.
Career low point: Losing his Dail seat in 1981.
What his supporters say: He's the most able and experienced contender, a polished media performer with the best public profile.
And his critics? They don't know what he stands for and say his only ambition is to gain and hold on to power.
Most famous quote: At the height of the government crisis in November 1994 over Harry Whelehan's appointment as President of the High Court, he went to Albert Reynolds and said: "We're looking for a head, Harry's or yours."
Little-known fact: He used to smoke a fat cigar every day after breakfast.
Brendan Howlin
Age: 41 Place of birth: Wexford
Education: CBS, Wexford, and St Patrick's Teacher Training College, Dublin.
Marital status: Single.
Political career: An unsuccessful candidate for the Dail in November 1982, he received a Taoiseach's nomination to the Seanad. Elected as a member of both Wexford Corporation and Wexford County Council in 1985, he was mayor of Wexford in 1986-87 and won a Dail seat in the 1987 general election. Labour chief whip from 1987 to 1993, he served as minister for health in the Fianna FailLabour coalition (1993-94) and minister for the environment in the rainbow coalition (1994-1997). Career high point: Presiding over a Department with more than £1 billion to spend, as minister for the environment, and launching a major programme for the restoration of pot-holed county roads.
Career low point: The collateral damage he suffered from the hepatitis C controversy. What his supporters say: They see him as highly principled with a long-term view, and say he would lead the Labour Party into opposition if he regarded it as being in the best interests of the party.
And his critics? They see him as somewhat arrogant, even swaggering. They claim he is sometimes influenced too easily by his civil servants. Most famous quote: At the height of the government crisis in November 1994, he was involved in a flurry of negotiations with Labour's Fianna Fail partners during the course of which he left "part of my anatomy out the window."
Little-known fact: He was named after Brendan Corish, the late Labour leader.