The US Secretary of State, Condoleezza Rice, has said "critical issues" would be tackled at a US-sponsored Middle East peace conference later this year.
The US is supporting Mahmoud Abbas while isolating Hamas
Speaking en route to Israel on her sixth visit to the region this year, Ms Rice said the talks would help lay the foundations of a Palestinian state.
Ms Rice is due to meet the Israeli PM, Ehud Olmert, and the Palestinian Authority President, Mahmoud Abbas.
With US encouragement, the two recently held a series of face-to-face meetings.
After their last meeting on 10 September, both leaders reaffirmed their commitment to a two-state solution and agreed to set up negotiating teams to discuss some of the issues in dispute.
Before arriving in Israel on Wednesday morning, Ms Rice said she hoped her brief trip would "build on the momentum" of those meetings and encourage both sides to resolve their differences ahead of the conference expected to be held in November.
"This meeting has to, in a substantive way, support the activities and the efforts of the parties to lay the foundations for the negotiation of a Palestinian state as soon as possible," she told reporters on the plane.
"I think everybody expects it to be serious and substantive. I think everybody expects it to address critical issues and we do not expect anything less."
The US is also giving financial assistance to build up the Palestinian Authority's security forces and is backing Tony Blair's efforts to develop Palestinian political institutions and the economy.
The BBC's Washington correspondent, Jonathan Beale, says the US has failed to address the political rift within the Palestinian Territories. The US is continuing to try to isolate Hamas, while others believe it must be part of any political process.
Ms Rice has not put forward any concrete proposals that would suggest the US has worked out a plan that would bring about a lasting peace, our correspondent says.