By Alan Johnston
BBC News, Gaza
For decades, Yasser Arafat's Fatah faction has been at the heart of the Palestinian political scene - the traditional party of power.
Fatah's different factions are finding it hard to agree
But now Fatah has big problems. It is divided, and widely seen as being in desperate need of reform.
Fatah's troubles were dramatically illustrated by television pictures that emerged recently from a West Bank hotel.
The footage showed a gathering of party activists called to discuss reforms.
But suddenly a group of armed Fatah men strode in and broke up the meeting. As one of the gunmen roared a furious speech, another started hurling chairs.
The message was clear. Reforming Fatah will not be easy.
But failure to reform could have drastic consequences for the party - and implications for the peace process.
When Palestinians were at their lowest ebb - in the aftermath of Israel's foundation - Fatah stepped forward.
Under Arafat, it began hitting back, and Palestinians respect the party for that role.
But its reputation has suffered during the decade that it has dominated the Palestinian Authority (PA).
In the eyes of many ordinary people, the PA's performance has been a story of corruption and incompetence - and Fatah has been tainted.
The party took a beating in January's local elections in Gaza.
Voters turned in large numbers to the militant Islamic movement, Hamas. It won landslide victories in nearly all the municipalities it contested.
Now Hamas has declared that it will also take part in the summer's parliamentary elections.
Fatah has just a few months to reform and rally its support ahead of what will be a crucial battle. The signs are that the campaign has not started well.
"I think it's very, very serious," says political analyst Sallah Abdelshafi. "it's becoming obvious that they can't agree on anything."
He says there is even a danger that Fatah will disintegrate.
Fatah's institutions are also in need of renewal
One of the party's leaders - currently jailed by Israel - Marwan Barghouti spelled out the problems.
He said Fatah lacked a culture of democracy and accountability. He called for real, radical reform and the rooting out of corrupt individuals.
Mr Barghouti represents a younger generation that led the first Palestinian uprising. Friction between this element and the dominant old guard is one of Fatah's major fault lines.
But former Palestinian ambassador and veteran Fatah member Adli Saadi says the generational split is not the main issue. He says the party is in dire need of restructuring along democratic lines.
The members of the two main decision-making bodies, the Central Committee and the Revolutionary Council, have been in place for around 15 years. Mr Saadi says there need to be elections as soon as possible.
But can Fatah reform?
"Theoretically it's possible," says Mr Abdelshafi. "But time is running out.
"There is Israel's disengagement from Gaza coming, along with municipal and parliamentary elections. Now they can't agree on the mechanism to nominate the candidates. There is basically disagreement on every level."
Fatah's troubles could have wider implications.
This is a time of renewed hope of progress towards an Israeli-Palestinian settlement.
Much of that hope has been inspired by the coming to power of Arafat's moderate successor, Mahmoud Abbas. But Fatah is his political powerbase.
As president of the Palestinian Authority, Mr Abbas may hope to be able float above the party
political fray to an extent.
But he might find that if Fatah were to do very badly in the summer's elections, he too will cut a more diminished figure.
Fatah's weakness is also opening the door to Hamas - and as its political influence grows, it will work to do everything it can to drive the hardest possible bargain in any talks with Israel.