JERUSALEM, July 8 — Mahmoud Abbas, the Palestinian prime minister, battled rival Palestinian leaders today to retain control of negotiations with Israel over a new American-backed peace plan, threatening to quit to face down a storm of criticism that he had gained little for renouncing violence.

Mr. Abbas abruptly canceled a meeting planned for Wednesday with Ariel Sharon, the Israeli prime minister, and some Palestinian officials said he might now harden his negotiating stance toward Israel.

Mr. Abbas´s allies said he was unlikely to follow through on his threat of resignation, which he has made in previous internal political fights. But he did step down today from the top governing body of Fatah, the faction he helped found with Yasir Arafat, the Palestinian leader.

In Washington today, the Bush administration prepared to provide funds to the Palestinian Authority for the first time, in an effort to help Mr. Abbas.

In a setback to the peace plan, known as the road map, the militant group Islamic Jihad claimed responsibility today for a bombing that killed a 65-year-old Israeli woman in her home on Monday night. The bombing, the work of a terrorist whose body was found at the scene, was the first such attack since the main Palestinian factions, including Islamic Jihad, announced on June 29 that they were suspending violence.

The stated reasons for the renewed killing and Palestinian political turmoil were the same: Palestinian anger that Israel had not agreed to release more of the thousands of Palestinian prisoners in its custody.

But Mr. Abbas was facing a broader challenge to his leadership, directed in part by Mr. Arafat, who reluctantly appointed him this spring under American and Israeli pressure, according to Palestinian and Western officials.

In meetings late into Monday night in the West Bank city of Ramallah, Mr. Abbas came under sharp attack from senior members of Fatah who are allied with Mr. Arafat, and from members of other factions. They said he had failed so far to extract significant concessions from Israel, Palestinian officials said. A central issue was the matter of prisoners, but the criticism covered his entire negotiating approach, which officials said was too indulgent of Israeli and American demands.

In response to the criticism, Mr. Abbas resigned today from the Central Committee, the top governing body of Fatah, and threatened to quit as prime minister.

One diplomat who was following the fight closely described Mr. Abbas as being "in a very tough-minded mood" and "tired of being pushed around."

Seen in that light, his threat to resign, made to Mr. Arafat, may have been a bluff to protect his authority. If Mr. Abbas left, his departure might cost the rest of the Palestinian leadership the new legitimacy Mr. Abbas has gained internationally, and particularly in Washington, through his pursuit of a cease-fire and the peace plan.

A member of the Palestine Liberation Organization´s top body, the executive committee, which also grilled Mr. Abbas on Monday night, said he now expected sharp disagreement with Israel. "Things are leading toward a crisis" with Israel, he said.

Israel is not obligated by the peace plan to release any prisoners, a move that is as noxious to Israelis as it is appealing to Palestinians. Yet in what Israel called an effort to support Mr. Abbas, it has begun releasing some prisoners, and on Sunday the government said it would free about 300 more, of more than 5,500 it is believed to hold.

But Israel said that it would give preference to people under 18 and over 60, and that it would release no one implicated in violence or connected to Hamas or Islamic Jihad.

Beyond the question of prisoners, some Palestinian officials accused Mr. Abbas of letting Israel dictate how the peace plan is put into action. They said he had allowed Israel to marginalize the three other members of the so-called quartet that drew up the plan with the Bush administration — the United Nations, the European Union and Russia.

Some officials also criticized Mr. Abbas for failing to push for a speedier Israeli withdrawal from areas of the West Bank that, according to the Oslo agreement, are supposed to be under Palestinian control.

In a sign of Israeli concern that Mr. Abbas´s position was precarious, Mr. Sharon´s government did not criticize his decision to cancel the Wednesday meeting. One Israeli official said the government viewed the cancellation as a move against other Palestinian leaders, not against Israel.

Mr. Abbas´s abrupt cancellation of the meeting — in the wake of Palestinian, not Israeli, violence — came in marked contrast to his genial appearance in public last Tuesday with Mr. Sharon, before their last meeting. Some Palestinian officials said Mr. Abbas got too far out in front of his own people with that appearance, in which he declared that Palestinians would pursue their dispute with Israel by "diplomatic means."

The Israeli reaction to the bombing on Monday night was also muted. The attack occurred in an Israeli village, Kfar Yavetz, near the boundary of the northern West Bank, where Israeli forces have not ceded security control.

Gil Kleiman, a police spokesman, said that the police were treating the bombing as a "probable suicide attack," but that it was unusual because it took place inside a home. The explosion killed the bomber and Mazal Afari, 65, the mother of eight. It also injured three of Mrs. Afari´s grandchildren.

While warning that a suicide bombing that killed more people would end the peace effort, Silvan Shalom, the Israeli foreign minister, told Israeli Army radio that this bombing was "not a huge attack" and said, "We have an opportunity now that we must not miss."

Islamic Jihad identified the bomber as a 22-year-old from the northern West Bank and claimed responsibility in a fax to The Associated Press. The fax warned, "Release the prisoners or the consequences will be grave." (Copyright 2003 The New York Times Company 07/09/03)