"I am concerned we could be offered less land. I asked Mr Bush during our talks to publicly reiterate his position for the creation of a state on lands occupied in 1967," Abbas told Reuters in an interview after the visit.
He said Palestinians would insist on being compensated with land inside Israel for any West Bank territory that Israel would seek to keep.
"We were also disappointed because U.S. officials did not show they were willing to press Israel to alleviate the lives of Palestinians by halting settlements' expansion and removing roadblocks, things that would give at least some credibility to the peace process," a senior Palestinian official said.
Following a recent visit by Rice, Israel announced plans to remove 61 of the hundreds of barriers it has erected in the West Bank. Israel says the obstacles prevent attacks by Palestinian militants. Palestinians call them collective punishment.
But a U.N. survey subsequently found that only 44 of the 61 barriers had been removed and that most of them were of little or no significance.
Aides said that despite his disappointment, Abbas intended to continue negotiating with Israel at least until the end of the year, although he feels a deal could be out of reach before the next U.S. president takes office.
If talks fail, the Palestinians would find themselves in a "very difficult position", Abbas told Reuters, voicing concern any momentum towards an agreement would be lost in the early days of a new U.S. administration.
Palestinian officials said Abbas would try again to persuade Bush to push Olmert harder for a deal when they meet in Egypt in mid-May after the U.S. president visits Israel to mark its 60th anniversary.
"We might have to seriously think now of a fallback position if we don't get a deal this year, at least to ensure continuity," one senior Palestinian official said.
Both sides are negotiating a framework agreement that would outline the shape of a future Palestinian state.
Abbas, whose Fatah faction lost control of the Gaza Strip to Hamas Islamists last June, and Olmert face stiff opposition to concessions, although both have powerful domestic incentives for trying to present at least the semblance of a peace accord.
Aaron Miller, a former U.S. official and Middle East peace negotiator, said he believed an agreement this year was possible "if the two sides are not that ambitious" about its scope.
