GAZA CITY, Gaza Strip ? Fury filled the dusty streets here Sunday as tens of thousands of Palestinians mourned the death of Hamas leader Abdel Aziz Rantisi, killed a day earlier by an Israeli missile strike not far from his home.

Punctuated by chanting and occasional gunfire, the angry funeral procession was similar in size and tone to that of Rantisi’s predecessor, Hamas founder Sheik Ahmed Yassin, who also was slain in an Israeli airstrike less than a month earlier.

Once again, Hamas promised to strike hard at Israel in revenge. Amid extraordinarily tight Israeli security after the Yassin assassination, the group did not carry out any successful attacks, spurring some to wonder if, in spite of its fiery rhetoric, it had lost some of its capability for organizing large-scale retaliation.

Hamas stalwarts insisted that Rantisi’s killing would not hobble the organization, which is popular on the streets of the Gaza Strip for its schools and social-service programs. Mourners lashed out at Israeli Prime Minister Ariel Sharon, calling him the “head of the snake,” and at President Bush and the United States. Many said they believed the United States had approved the killing in advance, despite American denials.

But the killing appeared to strengthen Sharon’s hand, giving him new momentum in the campaign to persuade members of his Likud Party to back his plan to evacuate all 21 settlements in the Gaza Strip and four others in the West Bank. Sharon still faces opposition, but on Sunday, he won the backing of two important swing votes: Finance Minister Benjamin Netanyahu and Education Minister Limor Livnat.

Before withdrawing from the Gaza Strip, Israeli officials hope to weaken Hamas, and Israel promised after the Yassin assassination that it would target the entire Hamas leadership.

On the streets of Gaza, a group of Palestinian women chanted, “Revenge! Revenge!” from the entrance of a shopping center. Hamas fighters in military-style fatigues carried Rantisi’s flag-wrapped body along a packed commercial street toward the city’s largest mosque.

A Hamas spokesman said the group had chosen a new leader to replace Rantisi, a 56-year-old physician known for his hard-line views toward Israel, but was keeping the identity secret for security reasons.

Israel already had vowed to carry out more of its “targeted killings” of militant leaders. Sharon on Sunday said he would continue a policy of “hitting the terrorist organizations and their leaders.”