Exit polls showed that Israeli Foreign Minister Tzipi Livni won with roughly 48 percent of the vote to take over the party led by Ehud Olmert.
The victory puts her one step closer to becoming Israel's next prime minister and only the second female premier, preceded by Golda Meir, whose term ended nearly 35 years ago.
Ms. Livni won the Kadima primaries with roughly 48 percent of the vote, exit polls from three different television channels predicted after polling stations closed at 10:30 p.m. on Wednesday. She beat her strongest competitor, Shaul Mofaz, by a margin of about 10 percent.
Livni will replace Ehud Olmert, who promised that he would leave office the day after party primaries were held, following demands he resign due to his likely indictment on corruption charges.
"A lot is dependent on her," Knesset member Ofer Pines told Israel's Channel One as the results came in. "If she can bring in new hope to the party and to the country, that would be great. If not, it's a real missed opportunity."