Israeli Foreign Minister Tzipi Livni is reported to have won the Kadima party election today.
The vote is to elect a successor to Ehud Olmert, who has vowed to resign after his party makes its choice.
Exit polls from three different television stations showed her winning 47-49% of the vote, with a lead of at least 10 points over her main opponent, Transport Minister Shaul Mofaz.
Ms Livni, who has been leading US-backed negotiations with the Palestinians, would have 42 days to form a government if she hopes to avert snap elections that polls say would bring the right-wing Likud party to power.
Her reputation for integrity has kept her out of the scandals that have plagued Kadima and Mr Olmert.
Two other ministers competing in the election trailed far behind.
The election, though decisive, looks unlikely to end the political turmoil brought on by graft accusations against Olmert, as it remains uncertain whether Livni will be able to form a government and take over the premiership.
The political turbulence further dims chances of reaching a Middle East peace deal by the end of the year, a goal Mr Olmert and Palestinian president Mahmud Abbas had set at a US conference that relaunched talks last November.
Mr Olmert had faced public uproar over a string of corruption investigations that could lead to criminal charges against him.
Kadima was expected to officially announce the name of its new leader early tomorrow if the winner polls at least 40%.
Otherwise, the top two vote-getters will head to a 24 September run-off election.
Mr Olmert is likely to wait until after the Jewish New Year celebrations and formally stand down early next month.
