Palestinians must act quickly to hold elections for a leader to replace Yasser Arafat if they are to peacefully transform their political system after more than three decades of one-man control, according to Palestinian politicians, academics and analysts.

But their ability to organize a free and fair vote within 60 days, as mandated by Palestinian law, will depend in large part on whether the Israeli government eases its occupation and controls of checkpoints and roadblocks in the West Bank and Gaza Strip, Palestinians said.

Arafat, considered the father of the Palestinian national movement and the symbol of his people's fight for an independent state, died Thursday at a hospital outside Paris. He groomed no successor, and his responsibilities were divided among four senior Palestinian leaders, all of whom lack Arafat's stature and charisma and whose legitimacy would be greatly enhanced by elections.

The speaker of the Palestinian parliament, Rawhi Fattouh, 55, was named interim president of the Palestinian Authority, the governing entity for the West Bank and Gaza, until a new president is elected. The other top leaders are Prime Minister Ahmed Qureia, 66; Mahmoud Abbas, 69, who was named head of the Palestine Liberation Organization; and Farouk Kaddoumi, 70, who was named leader of the Fatah political movement.

One Palestinian official called on President Bush to play an important role during the run-up to the election. "It's the first challenge for him and his credibility when he speaks about the larger issue of bringing democracy to the Middle East," said Saeb Erekat, the chief negotiator with Israel. In a joint White House appearance with Prime Minister Tony Blair of Britain on Friday, the day Arafat was buried, Bush pledged to work to encourage the creation of an independent and democratic Palestinian state.

Elections following Arafat's death represent the first step toward "reform and the transformation of the Palestinian revolution," said Mahdi Abdul Hadi, director of the Palestinian Academic Society for the Study of International Affairs. But Hadi said the success of elections depends partly on Prime Minister Ariel Sharon of Israel.

"If Sharon stops the killings and the incursions, releases Palestinian prisoners, lifts the siege over Jerusalem," which prevents most Palestinians from visiting the city, "and does not interfere with the upcoming Palestinian municipal elections in December, he will be endorsing this historic change and allowing moderates to rise," Hadi said. "If he doesn't, it will be a disaster."

Sharon has ruled out the possibility of releasing prisoners or making other such gestures, saying that the new Palestinian government must prove that it is serious about tackling terrorism before Israel will treat it as a partner for peace.

"Elections are not a substitute for fighting terrorism," a Sharon spokesman, Raanan Gissin, said Saturday. "To get to a democratic state, they have to fight terrorism."

"If they want to move away from the Arafat policies, they have to start doing something, and when we see that they're going in that direction, we'll be there to assist them," he said.

The Palestinians must overcome longtime rivalries and mistrust between Arafat's loyalists from the Palestinian exile community and a younger generation of reformers who grew up in the West Bank and Gaza Strip. Even deeper differences exist between Muslim militant groups, which have become popular and powerful during the Palestinians' four-year uprising, and the governing Palestinian Authority and Arafat's Fatah political movement, both of which are secular.

Qureia, a member of Fatah, has already begun fence-mending with the militant groups. He met with a dozen security chiefs and senior militant leaders in the Gaza Strip just before Arafat's death to discuss a more collective style of leadership.

Khalil Shikaki, a Palestinian political analyst and pollster, said it was important for the old guard and young reformers within Fatah to coalesce around a single candidate. He and other Palestinians said the likely choice was Abbas, who served as prime minister before Qureia.

"The old guard must forge an immediate coalition with the young guard and embrace them, allow internal elections for Fatah, and remove the old guard and Arafat cronies from the government," Shikaki said. Perhaps most important, he said, Israel should release the leader of the young reformers, Marwan Barghouti, who is serving a life sentence in prison for his involvement in the killing of five people.

"The most important element in organizing an election is a cease-fire, and Barghouti's help is going to be critical," Shikaki added. "Barghouti speaks for the young guard reformers, and to make the elections positive and to influence the outcome, he must be released."

Public opinion surveys show that, other than Arafat, Barghouti, a charismatic, firebrand orator and former head of Fatah in the West Bank, is about twice as popular as any other Palestinian politician, and his support will be crucial for Abbas or any other Fatah candidate.

Gissin, Sharon's spokesman, rejected the possibility of releasing Barghouti, saying: "His hands are tainted with blood. Would the United States release someone serving a life sentence to run for president?"

Barghouti did not recognize the legitimacy or legality of his Israeli trial, saying that because he was considered an enemy of the state, his guilt before an Israeli judge was a foregone conclusion.

"Marwan Barghouti hasn't decided what he's going to do," said Sa'd Nimr, the leader of the campaign to release him. If elected as the next Palestinian leader, Nimr said, Barghouti could appoint a vice president or deputy to rule in his place.

Correspondent Molly Moore contributed to this report.