Dahlan began losing standing in 2007, when the Islamic militant group Hamas, with amazing speed, routed forces under his command to take over the Gaza Strip. Persistent corruption allegations have also sapped his support among ordinary Palestinians. Still, he was allowed to relocate to the West Bank where he remained a close adviser to Abbas.

But two months ago, Abbas heard his former protege had criticized him in meetings with party activists, officials close to Abbas said. According to the officials, who spoke on condition of anonymity because of the sensitivity of the issue, Dahlan also called Abbas weak in meetings with Palestinian diplomats abroad.

Things fell apart quickly for Dahlan after that.

In November, Fatah set up a committee to investigate charges he was trying to form an anti-Abbas bloc inside the party. It also stripped Dahlan of his personal security guards — a huge slap for the man who once commanded thousands of Abbas' security forces in Gaza.

Last month, Fatah replaced Dahlan as the party's spokesman and barred him from participating in meetings of its highest body until the committee finishes its investigation. The interior minister also banned a TV station that Dahlan co-owned — Palestine Tomorrow — which was to begin broadcasting this month.