Jailed Palestinian leader Marwan Barghouti (search) reversed an earlier decision and took the first steps Wednesday to run for the presidency to succeed the late Yasser Arafat (search), throwing Palestinian politics into disarray.

Adding to the turmoil, the Islamic militant group Hamas announced that it will boycott the Jan. 9 election, the first sign of open tensions with the interim Palestinian leadership since Arafat died in France on Nov. 11.

If Hamas' tens of thousands of supporters abide by the boycott, it could undercut the legitimacy of the vote.

A candidacy by Barghouti, meanwhile, will likely split the ruling Fatah movement, which has backed the candidacy of interim Palestinian leader Mahmoud Abbas (search). Barghouti, a leader of the younger generation in Fatah, is more popular than the staid Abbas.

Barghouti's campaign on Wednesday paid a $3,000 deposit required from independent candidates, said Saed Nimr, head of a group devoted to freeing Barghouti from an Israeli prison.

Barghouti's wife, Fadwa, who visited him in prison Wednesday, was traveling to Ramallah to submit the formal papers for her husband's candidacy to the Central Election Commission, along with the required 5,000 signatures of support collected by his campaign, Nimr said. Because Abbas is Fatah's candidate, Barghouti would have to run as an independent candidate.

Barghouti, 45, is serving five consecutive life terms in an Israeli prison for his role in deadly shooting attacks that killed four Israelis and a Greek monk. Barghouti has denied involvement in violence.

Israel considers Barghouti a murderer and has said he won't be released from prison.

A Barghouti presidency would shake up the chances for resuming the peace process. Barghouti also favors a negotiated settlement, but has praised armed confrontation with the Israeli military. Abbas has been critical of the armed uprising against Israel and is eager to resume peace talks.

Barghouti has wavered repeatedly on whether to run. Several days ago, he announced he would drop out of the race for the sake of unity. When he did so, members of Fatah's young guard pledged to unite behind Abbas.

Barghouti's return to the campaign threatened to divide that united front in Fatah. Many young Fatah activists have complained that the long-entrenched Palestinian leadership has frozen them out of key positions.

Also Wednesday, Israel and Egypt reached agreement for Egypt to deploy 750 troops along its border with the Gaza Strip ahead of Israel's planned withdrawal from the territory, senior Israeli officials said.

The decision was made at a meeting in Jerusalem between Israeli Defense Minister Shaul Mofaz and Egyptian intelligence chief Omar Suleiman, officials said on condition of anonymity.

Israel's withdrawal from the Gaza Strip is to begin in July 2005, according to the government's "unilateral disengagement" plan.

Word of Barghouti's candidacy came just hours after Abbas formally launched his campaign for Palestinian Authority president.

Abbas called for a renewal of peace talks with Israel and said the two sides would meet after the election. "We must have a dialogue with the Israelis," Abbas said at his campaign headquarters. "After the elections, we will meet again" to discuss the road map.

The internationally backed peace plan calls for the establishment of an independent state next year, but has been stalled since it was signed in June 2003.

The Palestinians have failed to meet their commitment to crack down on militant groups like Hamas, while Israel hasn't kept its pledge to halt settlement construction and pull down settlement outposts.

Abbas indicated that he is ready to take action against the militants. "Every nation has opposition groups, but there are also laws and institutions," he said. "I am committed to having one authority and only one army and political pluralism."

He brushed off the Hamas boycott. Hamas sat out the first Palestinian general election in 1996 because it was a result of interim peace deals with Israel. Hamas opposes peace talks and is committed to Israel's destruction.

With the road map stalled, Israeli Prime Minister Ariel Sharon (search) has pushed forward with his plan to pull out of the Gaza Strip and four small enclaves in the West Bank.

Sharon initially envisioned the moves as a unilateral act, arguing that he has no Palestinian partner. But since Arafat's death, Sharon has expressed willingness to coordinate the withdrawal with the new Palestinian leadership.

However, Israel still wants Egyptian involvement as a mediator.

Details of the Egyptian troop deployment on the Gaza border — including the placement of the soldiers and the types of weapons they will be allowed to carry — will be decided at future meetings, Israeli officials said.

They said the deployment would not require a change in the Israeli-Egyptian peace treaty of 1979, which forbids the presence of Egyptian troops adjacent to Gaza. Instead, there would be facilitated by an exchange of letters between the sides.

Israel has been pressing for Egyptian help because it fears a Gaza withdrawal will leave a security vacuum. Gaza has been plagued by increasing chaos in recent months. Palestinian militants have also stepped up attacks on Israelis in the area in recent months to make it appear as if Israel is fleeing.