Abbas is Powerless Outside His Own Terrorist Group ?

The evidence is clear to those with an open mind. The problem is that most of the leaders of the US, Europe etc do not have an open mind at least on the subject of Abu Mazen. They believe that the President of the Palestinian territories is a moderate who has the power to make peace.
The evidence shows that neither is true.

Abbas is no moderate:

"The Al Aqsa Brigades commander Abu Ahmed said his group, including the militants launching rockets, is loyal to Abbas and coordinates "resistance operations" with the Fatah party. "The Al Aqsa Brigades is the military wing of the Fatah and the President Abu Mazen (Abbas) is the chairman of the movement," Abu Ahmed said.

And Abbas has no power to make Peace with Israel even if he wanted to:

Intelligence and Terrorism Information Center
at the Israel Intelligence Heritage & Commemoration Center (IICC)

A Hamas spokesman in an interview granted to an Iranian TV channel: Abu Mazen does not have full authority to engage in negotiations with Israel and Hamas will oppose any agreement reached in such negotiations

1. Ayman Muhammad Saleh Taha , a Hamas spokesman in the Gaza Strip, noted in an interview granted to an Iranian TV station that Abu Mazen does not have full authority to engage in negotiations with Israel and that Hamas rejects any agreement reached in such negotiations.

2. On April 17, Al-Alam, an Iranian TV channel in Arabic, broadcasted a talk show called Al-Mihwar (“the axis”). The show featured an interview with Ayman Muhammad Saleh Taha, a former Hamas operative who was held prisoner in Israel and is now one of the Hamas spokesmen and a member of the inter-organizational committee for preventing conflicts between Hamas and Fatah. In the interview, Ayman Taha was asked about Hamas's position on the contacts held by Abu Mazen with Israel . The highlights of his reply follow:

a. The stance of the Hamas movement has not changed and will not change regarding the “Zionist entity” and the meetings held by Abu Mazen with Israeli PM Ehud Olmert: “The movement is being very clear when it says that these meetings are pointless and do nothing to further the Palestinian cause.”

b. “The government platform is not the platform of Hamas, the Islamic resistance movement. The fundamental principles of the unity government are the lowest common denominator agreed upon by the Palestinian factions. We are saying loud and clear that the Hamas movement still considers itself the spearhead in the conflict with the oppressive enemy [ Israel ]. It will not relinquish its platform of resistance [i.e., violence and terrorism]…”

c. “In the strongest of terms, we oppose such negotiations and everything that will come out of it. We, the Hamas movement, will not agree to it, and I think these are clear, explicit statements already made by Dr. Mahmoud al-Zahar and by the head of the Hamas faction in the [Legislative] Council, Dr. Khalil al-Hayya. While they expressed their confidence in the government, they stressed that they had reservations about giving the president full authority in the negotiations…”

d. When asked what Hamas would do when Abu Mazen would reach an agreement with Israel and whether the Hamas movement would oppose the government that it heads, Taha replied: “Definitely. That is, we are saying that we will not accept any negotiations with the occupier on the fundamental rights of the Palestinian people and their legitimate rights. We will not bargain about those rights and will refuse to do so, whether in the government or in the Legislative Council…”