RAMALLAH, West Bank ? Palestinians marked the fourth anniversary of their uprising Tuesday amid signs that the extremist Hamas group is preparing a political challenge to Yasser Arafat despite a series of Israeli military blows at the movement’s leadership.

Hamas published newspaper ads urging supporters to vote in upcoming municipal elections, saying “it’s time for change.” And a top Hamas leader indicated the group might try to unseat Arafat in presidential elections, which have not yet been scheduled.

Meanwhile, Palestinian militants released an Arab-Israeli television producer for CNN a day after his abduction in the Gaza Strip. It remained unclear why he was taken hostage.

The kidnapping, coupled with Hamas’ electoral challenge, were apt reflections of the state of affairs in the West Bank and Gaza Strip after four years of fighting with Israel. The violence has left Arafat’s Palestinian Authority severely weakened, leading to widespread chaos and boosting Hamas’ popularity.

“We need an evaluation of these four years,” Palestinian Prime Minister Ahmed Qureia said. “Where have we been right and where have we been wrong? What did we achieve and what didn’t we achieve?” Qureia also called on Israel to reassess its policies.

The uprising erupted on Sept. 28, 2000, after Ariel Sharon, then Israel’s opposition leader, visited a sensitive Jerusalem hilltop revered by both Jews and Muslims. Palestinian riots broke out, and five months later Sharon defeated Ehud Barak in a special election for prime minister.

The fighting has taken a heavy toll on both sides, killing more than 3,000 Palestinians and nearly 1,000 Israelis.

A Palestinian militant of the Al-Aqsa Martyr's Brigades, a militia linked to Yasser Arafat's Fatah movement, participates in a parade to mark the fourth anniversary of the Intifadah, or uprising, Tuesday in the Gaza Strip.

Hamas is vying with other groups for a prominent role after the Israeli withdrawal from Gaza, where Hamas wields influence despite Israeli assassinations of its top leaders.

On Tuesday, Hamas published newspaper ads urging its followers to register to vote in local Palestinian elections, which are scheduled to begin Dec. 9. “Fellow citizens, it’s time for change. It’s time to register your name,” the ad said.