Sources familiar with the negotiations on Tuesday said President George Bush was expected to back the withdrawal as an interim step.
"There are understandings on key components," a diplomatic source said, adding the remaining issues would be worked out just before or during Bush's meeting with Israeli Prime Minister Ariel Sharon in Washington on 14 April.
The US-Israeli agreement was hammered out last week in talks in Jerusalem between Sharon and senior US officials.
One non-governmental source close to both the Israelis and the Americans said the White House planned to announce agreement on the "conceptual framework for the withdrawal."
The White House has said it sees the withdrawal as a "positive" and potentially "historic" interim step to help jump-start the stalled peace road map for the region.
US and Israeli officials have been negotiating the details of the withdrawal in almost weekly high-level meetings, and are seeking cooperation from Egypt, Jordan and others.
Both sides want to make sure the withdrawal does not allow the Palestinian resistance group Hamas to cement its grip over Gaza.
Sharon has proposed evacuating Israeli settlements in hard-to-defend enclaves in the Gaza Strip and setting up a new "security-line" in the West Bank.
While welcoming a pullout from the occupied land, the Palestinians have said unless Israel quits the West Bank entirely there is little hope of reviving the road map with its vision of Palestinian statehood by 2005.
Palestinians fear Sharon will annex West Bank settlement blocs in drawing what he has said will be a new security line.