WASHINGTON – The Israeli minister credited with influencing President Bush’s strategy on pressing the Arab world toward democratic reforms, Natan Sharansky, is leaving Prime Minister Sharon’s cabinet.

Citing his opposition to Mr. Sharon’s proposed withdrawal from the Gaza Strip, Mr. Sharansky resigned yesterday from his post as minister of Jerusalem and Diaspora Affairs. “Once again, we are repeating the mistakes of the past by not understanding that the key to building a stable and lasting peace with our Palestinian neighbors lies in encouraging and supporting their efforts to build a democratic society,” Mr. Sharansky wrote in a sharply worded letter to Mr. Sharon.

With Mr. Sharansky’s resignation, the Israeli government loses a persuasive communicator. Mr. Sharansky has held numerous high-level meetings with members of the Bush administration – including one with the president himself shortly after his re-election. Mr. Bush specifically requested a session with Mr. Sharansky after reading his book “The Case for Democracy: The Power of Freedom to Overcome Tyranny and Terror.” The book quickly became required reading at the White House; Secretary of State Rice quoted the volume in the testimony before her Senate confirmation hearing.

At the time, the State Department expressed reservations regarding the high-profile meeting because Mr. Sharansky had criticized the Gaza withdrawal policy that Mr. Bush has praised on numerous occasions. Mr. Sharansky’s co-author, Ron Dermer, told The New York Sun yesterday, “The president was fully aware of Natan’s position on disengagement.” Mr. Dermer, who attended the meeting, added that both Mr. Bush and Mr. Sharansky agreed that peace and stability in the Middle East were correlated to the spread of democracy. “Despite the tactical differences over disengagement, it was clear what the goal was,” Mr. Dermer said.

In his letter to Mr. Sharon, released to the public yesterday, Mr. Sharansky was particularly critical of his government for failing to make Gaza withdrawal conditional on democratic concessions from the Palestinian Arabs. “Not only does the disengagement plan ignore such reforms, it will in fact weaken the prospects for building a free Palestinian society and at the same time strengthen the forces of terror,” Mr. Sharansky wrote of what he called a “tragic mistake,” calling it “absurd” that “Israel, the sole democracy in the Middle East, still refuses to believe in the power of freedom to transform our world.”

An Israeli politics expert at the Hudson Institute, Meyrav Wurmser, yesterday said that Mr. Sharansky “rises above politics and will continue to be the democratic conscience of Israel.” Nonetheless, she admitted that he and other Israeli political leaders opposed to the disengagement feel demoralized. “He lost within his party. The far right has a level of frustration that there is a little they can do. The last thing they have left is to withdraw from public life.”

Mr. Dermer agreed with Ms. Wurmser’s assessment. “The political process was over,” he said. “As he sat in the government, it became clear that the glue that holds the government together is the disengagement plan. Rather than sit for three months in the government to wait for the government to implement a policy he does not believe in, he decided to leave.”

While the former Soviet political prisoner has been feted at the White House as an intellectual leader, in the rough-and-tumble world of Israeli politics, Mr. Sharansky has failed to secure major political positions. He has a small following comprised of fellow Russian immigrants inside his political party, Yisrael B’Aliyah. In his letter, he thanked Mr. Sharon for incorporating the small party into the Likud.

Mr. Sharon yesterday began his Cabinet meeting by publicly thanking Mr. Sharansky for “outstanding work in advancing the issue of dealing with anti-Semitism throughout the world,” the Israeli newspaper Ha’aretz quoted the prime minister as saying. Mr. Sharansky led a diplomatic campaign that helped persuade America and France to pull the license for Hezbollah’s satellite television station, Al-Manar.

Inside Israel, Mr. Sharansky could emerge as a new leader of a settler movement that Mr. Sharon once led inside Jerusalem during the peace process of the 1990s. Defeated politically inside the Knesset, settlers have promised to use civil disobedience to halt the proposed dismantlement of Gaza settlements this summer.

In his letter, Mr. Sharansky made no reference to the settlers. Israel’s Army Radio yesterday reported that Mr. Sharansky will remain a member of parliament for Mr. Sharon’s Likud party.