Prime Minister Ehud Olmert intends to hand his resignation letter to President Shimon Peres the day after the September 17 Kadima primary and ask him to entrust the new party leader with forming a new government, Olmert's associates said Wednesday night. They spoke soon after the prime minister had made a somber speech at his official residence in Jerusalem in which he announced that he would not seek to retain the leadership. By law, Olmert will remain prime minister until a new government is formed. If the new Kadima leader forms a government soon after the primary, Olmert will then leave office. But if no new government is established, Olmert, despite having formally tendered his resignation, could remain prime minister until after a general election that would likely be held in spring 2009. Olmert decided 10 days ago to announce his imminent departure on Wednesday - to coincide with the last day of the Knesset's summer session and the Kadima election committee's formal decision to set the September 17 date for the primary. He kept his decision a secret. However, before his speech, Olmert called US President George W. Bush to inform him of his impending move, he briefed his lawyers, and his office alerted the four Kadima leadership candidates. "He didn't want to humiliate himself by waiting until the last minute as some people thought he would," an Olmert associate said. "He is the most realistic person in the world. He didn't want to look like he cared only about himself by staying as long as possible. He decided he wanted to play the responsible adult." The Jerusalem Post reported exclusively in its lead story Wednesday that Olmert would decide his political future "very soon." In his 8 p.m. speech, broadcast live here and abroad, a defiant and almost tearful Olmert lashed out at Foreign Minister Tzipi Livni and other adversaries without naming them and vowed to keep the peace process with the Palestinians and Syria moving forward until he left office. He referred bitterly to his opponents as "self-styled fighters for justice." "As a citizen in a democratic state, I have always believed that when a person is elected prime minister in Israel, even those who opposed him in the ballot box would want him to succeed," Olmert said. "But instead of enjoying this basic level of faith, I found myself, immediately upon being elected, subjected to a wave of investigations, probes and criticism. Almost from my first day in the Prime Minister's Office, I was forced to repel personal attacks, even as I was busy making fateful decisions regarding Israel's security and existence." Olmert recounted the successes of his premiership and insisted that his personal work had not been harmed by the investigations against him, but lamented that his adversaries had gotten in his way. "At the same time, I was forced to defend myself against relentless attacks by self-styled fighters for justice who sought to oust me from my job and saw all means as justifying of that end," he said. "Things have gone out of all reasonable proportion. Have I made mistakes over the many years of my activities? I certainly have! And I regret them, and I am sorry," he said. "But does the picture presented to the public fairly reflect the reality? Absolutely not!" Olmert said he was proud to be a part of a nation in which a prime minister could be investigated like any other citizen. He agreed that the prime minister was not above the law, but said he was also not below it. "To my profound sorrow... correct procedure does not take place in [our country]." he said. "Maybe I today, in my personal decision, have opened a portal to a more appropriate reality." Turning to diplomacy and foreign policy, Olmert said, "We are closer than ever to firm understandings that can serve as a basis for agreements on two [diplomatic] tracks: The Palestinian and the Syrian... As long as I serve as prime minister, I will not desist from the effort to bring the negotiations between us and our neighbors to a successful conclusion that offers hope. "As prime minister, I bear ultimate responsibility for every decision. There are many excellent people in the country, and together with them I have championed far-reaching, daring and complex processes... Most of them are unknown to the majority of the public, but they are well-known to those who were part of the decision-making and operational process." Olmert said he would not interfere with the Kadima leadership race or with the victor's effort to form a government. Transportation Minister Shaul Mofaz, one of the two leading candidates to replace Olmert, said the prime minister had made a "brave decision." "This proves that he puts the good of the country first, despite his personal pain," Mofaz said. "Kadima members have a heavy responsibility to pick the next prime minister. I am sure they will take that responsibility seriously." A source close to Mofaz said Olmert had helped him politically by making clear to Kadima members that they would be electing a prime minister and not just a party chairman, a message that Mofaz had intended to emphasize in his campaign. While Livni's associates have said that Olmert's constant attacks on her would boomerang and help her politically, sources close to Mofaz said the attacks would have no impact, because the prime minister's opinion of Livni was clear and was no longer relevant. Livni, the other leading candidate in the Kadima primary, canceled a press conference that she had intended to give in Washington, but her office released a statement. "It was not a simple decision for Olmert, but it's the right one," Livni said. "Kadima must take action to ensure that its unity is maintained in the election process so we can continue leading Israel." Public Security Minister Avi Dichter, who is also running for Kadima chairman, said the prime minister had made the right decision for the nation and personally, and expressed confidence that whoever won the primary would lead the country well. The fourth candidate, Interior Minister Meir Sheetrit, said he had called the prime minister and told him he was sad that he was leaving in such a manner. He thanked Olmert for not endorsing a candidate and wished him well in his quest to prove his innocence. Labor chairman Ehud Barak also said Olmert had made a correct and proper decision. His associates took credit for starting the process that led to Olmert's departure by insisting that Kadima replace him. Olmert's announcement will intensify the Kadima race, which was already expected to advance to the next level on Thursday when Kadima's membership drive ends. The drive is expected to end with more than 70,000 Kadima members who will be entrusted with selecting the next party leader and perhaps the next prime minister.