This week proved to be an especially deciding one for Israel, the Palestinians and perhaps even neighbouring Arab states, writes Graham Usher from Jerusalem Let the people decide What was once a shoo-in is now an election. But why Marwan Barghouti changed his mind? The unity so carefully crafted by the Palestinian leadership following Yasser Arafat's death is looking a little frayed. On 1 December -- one week after endorsing Mahmoud Abbas (Abu Mazen) as Fatah's "only" official candidate -- jailed West Bank Fatah leader, Marwan Barghouti, announced that he would challenge him for the Palestinian Authority presidency. The same day saw Hamas call on its followers to boycott the 9 January poll. The smaller Islamic Jihad urged the same next. The Islamists' protests were that no official date has been set for parliamentary elections, as well as over changes in the electoral law that (they charge) will benefit the existing Palestinian leadership rather than a new "united" one. Barghouti's original, mulled threat to stand for president had been driven by similar concerns. Like many in Fatah, he had been angered by the way Abbas had been chosen. It had remained the prerogative of Fatah's Central Committee (FCC) and Revolutionary Council (FRC), two institutions dominated by the so- called "old guard" or those "outside" Fatah leaders who had returned from exile with Arafat and who derived their position (and privileges) solely from him. Barghouti has historically represented the "insiders": Fatah activists native to the West Bank and Gaza who came to the fore in the first and second Intifadas but feel underrepresented in Fatah constituent bodies, above all, the FCC and FRC. Like them, Barghouti said the proper way to elect Fatah's candidates was by primaries throughout the movement. But a trade was made. In return for Barghouti standing down -- and throwing his weight behind Abbas -- Abbas overturned objections from the FCC not only to hold parliamentary elections in May but also (and for the first time in 15 years) internal elections in Fatah, where "the outside leadership would be thanked for its contribution to the Palestinian cause and told goodbye," in the words of one Fatah "insider" leader. So what made Barghouti again change his mind? Barghouti's wife, Fadwa, says it was only after her husband had received "hundreds of messages encouraging him to run from the Fatah grassroots and other Palestinian organisations". But Fatah leader and Barghouti aide, Ziad Abu Ein, gives another explanation. "As soon as he backed Abu Mazen and returned to his cell, Marwan realised he had made a mistake. When he was contemplating running for the presidency, he saw the PA exert all kinds of pressures on Israel and the Americans to have him freed. But once he had endorsed Abu Mazen, the pressures stopped. He realised he had played his only card without getting anything in return -- that, while he was strong with the grassroots, he was weak with the leadership." Can he win? As the official candidate, Abbas has Fatah's establishment behind him as well as the enormous powers of patronage that go it: he has received support not only from the FCC and FRC but also from what were once "insider" strongholds such as Fatah's parliamentary deputies, the prisoners and militia leaders like Zakeria Zubeidi, head of Al- Aqsa Martyrs Brigades in the northern West Bank. All variously accuse Barghouti of dividing Fatah; some have called for his resignation. The Palestinian middle class too is largely with Abbas, viewing his opposition to violence, support for law and order and sound relations with Israel, America and the Arab world as assets rather than liabilities. But straw polls show Barghouti has support among the young, the poor, students, prisoners, their families and refugees, whose "right of return" to homes in what was pre- 1948 Palestine but is now Israel he has vowed to defend. For these constituencies he remains the only authentic heir to Arafat, committed to a two-state solution with Israel while insisting on his people's right to resist occupation by all means. He may also pick up the vote of the Islamists, who will find it hard to disagree with his vow to "maintain the path of the Intifada and the resistance and protect them from being labelled terrorism". Dr Khalil Shikaki -- whose Palestinian Centre for Research and Surveys has regularly polled Barghouti as the most popular Palestinian politician in the occupied territories after Arafat -- believes Barghouti can win the presidency "if he decides to take it to the end". But he is unsure whether Barghouti's candidacy is just "jockeying" to get him and the other Palestinian prisoners released and force political and electoral reform on Fatah. "If Barghouti gets what he wants from Israel and the old guard, he will withdraw from the race," he predicts. Abu Ein accepts that Barghouti's off-again on-again candidacy has cost him support but insists Barghouti "will run until the end of the election". And this is because he wants to give his people not only a choice between candidates but also between policies. "Marwan supports negotiations with Israel only if they end the occupation. Otherwise the Intifada must continue. Abu Mazen is against any kind of struggle. He believes only negotiations and international pressure will force Israel to accept a Palestinian state. In running for presidency Marwan is saying to Abu Mazen: 'Fine: you have your way and I have mine. Now let the people decide'."