Ehud Olmert, 60, acting prime minister, finance minister and former mayor of Jerusalem, is seen as a pragmatist, likely to continue Sharon's policy of withdrawal from occupied Palestinian urban centres while building up the main illegal Jewish settlements in the West Bank close to Israel.
Olmert followed Sharon when he left the hardline Likud party to form the centrist Kadima party. Olmert, a lawyer and veteran legislator, was Sharon's staunchest ally during the prime minister's transformation from hawk to moderate.
As Jerusalem mayor from 1993-2003, Olmert filled one of Israel's most sensitive jobs, balancing conflicting Jewish and Palestinian interests and wrestling with constant budget shortfalls by raising money abroad.
He has served in Sharon's government since 2003, when he was appointed vice premier and minister of industry, trade and labour. He took over as finance minister last August following the resignation of Benjamin Netanyahu, Sharon's main rival in Likud.
An opinion poll published on Thursday showed Kadima winning 40 of 120 parliamentary seats if headed by Olmert.
Benjamin Netanyahu, 56, a former prime minister who succeeded Sharon as leader of Likud, quit his post as finance minister in Sharon's government last year, citing his opposition to Sharon's Gaza's withdrawal.
Netanyahu is against a fully
independent Palestinian state
Netanyahu was prime minister from 1996-99, a period marked by an economic slowdown and little progress in peace negotiations. His tenure was marked by friction with the Palestinians, the media and infighting with other Likud members.
Born in Tel Aviv, he moved with his family to the United States as a teenager, speaks fluent English and holds a master's degree in business management from the Massachusetts Institute of Technology.
He has said that the Palestinians could receive a large degree of autonomy, but not the fully independent state they are demanding and which Sharon has said is inevitable.
Shimon Peres, 82, vice-premier, former prime minister and winner of a Nobel prize for his peacemaking efforts.
Shimon Peres won a Nobel prize
for his peacemaking efforts
Polls show that if Peres were to lead Kadima into the March election, the party would take 42 seats. However, Peres has never managed to win an election and was deposed as leader of the Labour party by Amir Peretz, a union leader last year.
Peres, a member of parliament since 1959, is feted abroad as a statesman and shared the 1994 Nobel Peace Prize with prime minister Yitzhak Rabin and Palestinian president Yasser Arafat.
At home, however, he is renowned for his multiple electoral defeats. He served three brief stints as prime minister, twice replacing Rabin and once as part of a rotation agreement with a hardline rival after a deadlocked election.
He also lost a parliamentary vote for Israel's ceremonial presidency, an office that would have given him a dignified exit from politics.
Amir Peretz, 53, won a surprise victory in a Labour party primary in November. He is widely perceived as strong on social issues but weak on matters of war and peace.
Amir Peretz immigrated to Israel
from Morocco in 1956
Peretz immigrated with his family to Israel from Morocco in 1956, and settled in the Israeli working class town of Sderot, on the edge of the Gaza Strip. He earned his high school diploma, reached the rank of captain in the army and was elected to Israel's parliament on the Labour slate in 1988.
In 1995, the father of four became head of the Histadrut Labour Federation.
Peretz often speaks of growing up in poverty and his rant against Israel's free market policies has earned him support among those hurt by the growing gap between rich and poor as well as the ridicule of others who see him as a throwback to a bygone era of big-brother socialism.
Tzipi Livni, 47, justice minister, a rising star in Israeli politics and a protégé of Sharon. Like Olmert, she followed Sharon to Kadima. Polls indicate that if she were to head the party it would win 36 parliamentary seats.
Livni spent four years with
the Mossad intelligence agency
A law graduate, Livni spent four years working at the Mossad intelligence agency. Since 2001 she has held a number of portfolios in Sharon's government, among them agriculture, housing, regional development and immigrant absorption.
The youngest of potential successors to Sharon, she is a regular TV interviewee and enjoys widespread popularity with the Israeli public.