The mainstream Palestinian movement Fatah came together here on Tuesday for a landmark three-day gathering, its first in 20 years and its first ever on Palestinian soil.

The opening ceremony was festive and emotional, though the celebratory tone did not dispel the difficult situation Fatah found itself in. It has struggled to recover from a humiliating defeat by Hamas, its Islamic rival, in the 2006 elections and the subsequent loss of Gaza. Fatah continues to be riddled with internal divisions, and many participants said the conference might be the movement’s last chance to revive.

“We have made mistakes,” said Mahmoud Abbas, the Palestinian president and leader of Fatah. “Twenty years is too long.” The conference, he said, should be a “platform for a new start.”

About 2,000 delegates from all over the world are attending the conference, at a school near Manger Square. Israel, which controls the West Bank borders and is interested in bolstering the more moderate Palestinian forces, allowed in Fatah members from hostile states like Syria.

Yet Hamas prevented hundreds of Fatah delegates from leaving Gaza to participate, a decision that has deepened the Palestinian divide.

In order to confront dual challenges — Hamas and setbacks in the peace process with Israel — the Fatah delegates want to use the conference to devise a clearly defined, unifying program for the movement and to elect new representatives for its decision-making bodies. The rank and file wants to inject new blood into the moribund leadership committees; many of their members have died over the years.

Dimitri Diliani, 36, a Fatah activist from Jerusalem who is vying for a seat on the Revolutionary Council, the Fatah parliament, said new leadership would “at least try to do better than the 20-year-old one.

“Anything is better.”

The day was filled with contradictory messages reflecting the disarray in Fatah. A huge poster on the wall bore the legend “Resistance is the legitimate right of our people” alongside a black-and-white photograph from the 1960s of a Palestinian youth with a gun.

Mr. Abbas reminisced about the early years of armed struggle against Israel. But he also stressed the need for new, more appropriate forms of resistance while pursuing negotiations for an independent Palestinian state. He blamed a lack of discipline in part for Fatah’s failures.

A stickler for law and order, Mr. Abbas also proudly noted that Palestinians now wear their seat belts, or face being fined.

As his speech rambled into its second hour, the air filled with cigarette smoke; people started dozing off, milling around and leaving the hall.

Mr. Abbas is a pale successor to Yasir Arafat, the deceased Palestinian leader and founder of Fatah. Mr. Arafat, a fiery orator and a revolutionary at heart, would never have spoken of seat belts. His picture peered down at the conference proceedings, and every mention of him was greeted with rapturous applause.

Yet Mr. Abbas has proved to be a reliable leader. He said he was proud to have been by Mr. Arafat’s side in making the decision to begin an armed struggle in 1965. But he said that Fatah had since moved on to political pragmatism and the pursuit of international legitimacy.

Mr. Abbas made it clear that resistance should be limited, taking the form of popular protests and demonstrations like those held weekly against Israel’s security barrier in Bilin and other villages of the West Bank.

The concept of the armed struggle is likely to be the subject of heated debate at the conference. Many members want Fatah to remain a liberation movement until the goal of a Palestinian state has been achieved.

“We want to combine politics and resistance until the Palestinian national project is complete,” said Ismail Tilawi, a delegate from Ramallah.

The younger generation of Fatah has been agitating for a party conference for years. Given the weakness of the movement, the fact that it is taking place in the West Bank is widely seen by Palestinians as a victory for Fatah and Mr. Abbas.

Now the Palestinians — like the Israelis and the international backers of Fatah — are waiting to see the results.

“Having the conference at all is a miracle, and having it in the homeland is another miracle,” Mr. Abbas said. “But the outcome of the convention is more important than these two miracles.”