Palestinian gunmen linked to the ruling Fatah movement killed one of their party leaders Tuesday, increasing tensions on the eve of parliamentary balloting and raising doubts about a new pledge by armed groups in the West Bank and Gaza to hold their fire during the vote.

Opinion polls have shown Fatah and Hamas in a close race ahead of Wednesday's election and both sides have said they might form a coalition government. Candidates were banned from campaigning Tuesday for a cooling-off period before the election.

Mushir al-Masri, a Hamas candidate in northern Gaza, said the Islamic group expects to become the largest party in parliament. But it will not try to form a government alone, instead seeking a partnership with Fatah or other parties, he said.

Top Hamas leaders spoke with Palestinian leader Mahmoud Abbas recently to discuss the elections and their aftermath, he said, without giving details.

Meanwhile, Abbas called on all Palestinians to exercise their right to vote.

"The election is a right and duty at the same time, and I hope that the results of this election will reflect honestly the Palestinian people's opinions," he said in the West Bank town of Ramallah.

Thousands of Palestinian security personnel, who voted early, fanned out across the West Bank and the Gaza Strip to protect polling stations. More than 1,700 Israeli border police are being deployed to ensure order and the free movement of voters in the Jerusalem area during election day, Jerusalem police spokesman Shmuel Ben-Ruby said.

Violence has marred the period before the elections, with militants taking over government offices and threatening poll workers. Much of the unrest was carried out by gunmen linked to Fatah, apparently fearing losses to Hamas.

Fatah also has been riven by internal divisions, which turned deadly Tuesday. Fatah gunmen shot to death Abu Ahmed Hassouna, 44, a party leader in Nablus after he told them to stop shooting at campaign posters on his house, relatives said. It was the second politically motivated killing of the campaign.

About 1,000 people marched to the main police station in Nablus to protest the shooting, giving the police chief a letter demanding an end to lawlessness. "Enough, enough. We want the police to protect us." they shouted. Dozens of gunmen later blocked a main road and shopkeepers shut down their stores in protest.

In Tulkarem, about 40 militants from Islamic Jihad — which is boycotting the vote — marched along the West Bank town's main road to demand the release of prisoners from Palestinian jails and to ask residents to boycott the election. Many wore fake explosive belts and carried wooden sticks.

Police, claiming one of the passing protesters shot at their station, opened fire on the group, scattering the masked men. No one was hurt.

The violence cast doubts on the fragmented militant factions' promises to maintain calm on election day.

About 25 masked gunmen from various factions held a joint news conference Tuesday in Gaza City to announce they would be unarmed during the balloting.

"Everyone agreed to keep the election process moving in a smooth, clean and honest way in order to create the fundamental basis for a political partnership," said Abu Obeida, a Hamas spokesman.

Abu Adham, a spokesman for the Fatah-linked Al Aqsa Martyrs' Brigades, said all groups want the elections to succeed, "and we have to contribute to protect it."

"The only ones who must have weapons are the uniformed security officials and we will be supporting them," Adham said.

Islamic Jihad did not attend.

Hamas, known for its suicide bombings and calls for Israel's destruction, has emerged as a formidable political force, attracting voters with calls for clean government and an end to Fatah's corruption, while pointing to its own popular social and education programs.

Hamas has said if it wins a majority, it would form a coalition and take only low profile, service-related Cabinet posts and let Abbas deal with Israel. Israeli officials have said they will not deal with Hamas until it disarms and renounces violence, a vow that could complicate hopes for restarting peace talks.

In a statement clearly aimed at Hamas, Secretary of State Condoleezza Rice said Monday that Palestinian voters should bear in mind that terrorism is not a "pathway to peace."

"The United States won't change its policies toward Hamas," she said, implying the Bush administration would not work with a Palestinian government dominated by Hamas. But she did not rule out cooperating with a government that had some Hamas ministers.

The main road in the northern Gaza town of Beit Hanoun was decorated Tuesday with green Hamas flags, yellow Fatah flags, and red, green, black and white Palestinian flags. The display was orderly, and equal space was given to all.

Ahmed Saadat, a 24-year-old policeman, said he reconsidered his plan to vote for Hamas because the militant group's softer line in recent weeks began to resemble Fatah's platform.

Although Fatah has made "countless mistakes," Saadat said, "at least Fatah has tried to bring us peace, and Fatah is known to everyone." He spoke near a field Israel pounded with ordnance because militants used it to launch rockets.

Saadat was among the security personnel who voted early. Officials said 91 percent of security officials voted.

In nearby Beit Lahiya, support for Hamas was clear. The group set up a makeshift headquarters in a green tent next to a mosque in the center of town.

Nearby, a large poster showed nine members killed in fighting with Israel, a large, green Islamic crescent carved in wood and the number "6" — signifying the party's place on the ballot.

With many Palestinians weary after five years of fighting with Israel, Hamas has played down its violent ideology. But appealing to its hard-line core, leaders say they remain committed to armed struggle.

Fatah officials have said they expect to lead a coalition government, preferably with smaller parties. They say they will join Hamas only if it allows peace talks to resume with Israel.

Hamas' participation has created friction with Israel, the U.S. and the European Union, which all brand Hamas a terrorist group.