Monday's fierce clashes between Fatah and Hamas - the worst since the Islamist movement's violent takeover of the Gaza Strip last June - are a reminder of the huge challenges facing Palestinian Authority President Mahmoud Abbas on the eve of the US-sponsored peace parley in Annapolis, Maryland. The fighting shows that Fatah and Hamas are far from resolving their bloody power struggle despite reports of Arab and Islamic mediation efforts and secret negotiations between the two parties. It also shows that Fatah, which managed to bring tens of thousands of Palestinians to a rally marking the third anniversary of Yasser Arafat's death, is still capable of flexing its muscles in the Gaza Strip. Buoyed by the large turnout, Fatah officials said Monday's clashes were a sign of the growing predicament of Hamas. They explained that Hamas's "hysterical" response to the rally was a sign of the movement's fear of losing control over the Gaza Strip. Undoubtedly, the clashes are seen as a PR disaster for Hamas, which is now being accused by some Palestinians of suppressing a "peaceful" rally in honor of Arafat. Scenes of Hamas militiamen opening fire at Fatah supporters and beating them on the streets of Gaza City are likely to alienate many Palestinians. In the past few days, Fatah has exploited ceremonies to commemorate Arafat to wage a campaign against Hamas. At speeches in Ramallah and Gaza City, Fatah representatives and leaders declared that the countdown for Hamas's "coup" in the Gaza Strip had begun. "Hamas is isolated and facing a serious crisis," said a senior Fatah official. "That's why they didn't hesitate to open fire at Palestinians participating in the rally in the Gaza Strip. Monday's bloody events show that Hamas is aware of the growing disillusionment with its rule." Hamas leaders, on the other hand, are convinced that Fatah, with the help of Israel and the US, is still trying to undermine the Hamas government in the Gaza Strip. According to Hamas spokesmen, Fatah has been using the Arafat rallies to incite against Hamas. "Fatah is trying to take the Gaza Strip back to the days of anarchy and lawlessness," said Ihab al-Ghissin, spokesman for the Hamas-controlled Interior Ministry. "Their goal is to overthrow the legitimate government of Hamas, but they won't succeed." Another Hamas official, Islam Shahwan, claimed that Fatah gunmen were the first to open fire at Hamas's security forces. He said the gunmen were operating on instructions from the Fatah leadership in Ramallah with the aim of dragging Hamas into a confrontation. The proposed peace conference in Annapolis has only escalated tensions between Fatah and Hamas, whose leaders have stepped up their attacks on Abbas, warning him against making concessions to Israel at the parley. Hamas's main argument is that Abbas does not have a mandate to negotiate with Israel over explosive issues such as the status of Jerusalem, the "right of return" for refugees and the borders of the future Palestinian state. The deepening divisions among the Palestinians cast a serious shadow of doubt over Abbas's ability to deliver at the Annapolis conference. Moreover, the severe crisis raises questions about Abbas's ability to sell any agreement with Israel to the Palestinian public.