The talks have already faced challenges even before they start. Both Abbas and Palestinian chief negotiator Saeb Erakat had said if Israel continues to build settlement, direct talks will collapse.

Israeli Prime Minister Benjamin Netanyahu (L) speaks during a press conference about the Middle East peace talks as U.S. President Obama looks on at the East Room of the White House in Washington D.C., capital of the United States, Sept. 1, 2010. [Zhang Jun/Xinhua]

However, Netanyahu said on Tuesday during meeting with Clinton that he will not extend the settlement moratorium which expires on Sept. 26.

The upcoming talks were further overshadowed by the killing of four Israelis on Tuesday by a gunman near the West Bank city of Hebron.

However, Obama's Middle East special envoy George Mitchell argued on Tuesday that allowing the Israeli-Palestinian conflict to continue indefinitely was more risky than making hard decisions to make a peace deal.

Mitchell said setting a one-year timeline for the talks was intended to remind everyone that the peace process should not drag on forever.

"It's very important to create a sense that this has a definite concluding point. And we believe that it can be done," he said.