Olmert said instead he will resign once his successor is determined, The Jerusalem Post reported.

"As a citizen in a democracy I have always believed that when a person is elected prime minister in Israel, even those who opposed him in the ballot want him to succeed," he said. "But instead I found myself subjected to constant investigations and criticism. Almost from day one, I had to repel personal attacks and postpone decisions that are pertinent to the security of the state."

Olmert also ticked off some of the successes he said his administration has won, noting that "Israel's position has improved" under his premiership.

"The North enjoys tranquility; Israel's deterrence has immeasurably improved. I am proud of these achievements," he said.

"In the social-economic field, we have maintained a stable economy and made some impressive progress," he added. "We have increased the war on poverty, allotted a bigger budget for education, increased welfare payments for the elderly, took care of Holocaust survivors."

The winner in the Kadima primary will have until October 26 to submit his new proposed government to President Shimon Peres for approval.