In a move reflecting "frustration and bitterness", the U.S. administration is considering sending Israel a letter listing unfulfilled obligations and promises.

A senior American source said that the administration is frustrated over Israeli Prime minister Ariel Sharon's failure to evacuate the illegal outposts or freeze the construction in the settlements, as he had promised.

The letter to Israel is intended to remind Israel that the American administration's expects a swift implementation of obligations.

Senior administration officials accuses that Sharon is taking advantage of the fact that the U.S. is in an elections period, knowing it will not worsen the relations with him.

Israeli newspaper Haaretz quoted A senior American source as saying "When President Bush is elected for a second term he will no longer treat Sharon as he did the first term if the promises are not kept."

Administration sources say that for 18 months Sharon's promises have not been kept and this is harming his credibility and status in Washington.

An Israeli official source said that Israel intends to ask the Bush administration for a different understanding that allows Israel to expand major settlement blocs.

U.S. complains came ahead of Negotiations slated to begin in coming weeks on demarcation of construction borders for each West Bank settlement.

Israeli plans to demand a special status that allows Israel to expand major settlement blocks parallel to the implementation of the disengagement plan.

A senior Israeli political official cited Ma'aleh Adumim, Gush Etzion, Ariel, Immanuel, Betar Ilit, and Modi'in Ilit as examples of such blocs.

Israeli Defense Ministry confirmed Monday the approval of 600 new housing units in the West bank settlement of Ma'aleh Adumim after Sharon gave his go ahead a month ago.

The White House's Senior Director for Near East Elliott Abrams is due to arrive in Israel on Thursday.

Abrams is scheduled to meet Sharon and Foreign Minister Silvan Shalom to discuss issues related to the West Bank separation wall, Israel's settlement construction, unauthorized settlement outposts, and the humanitarian aspects of West Bank and Gaza Strip checkpoints.

"We continue to pressure them [ Israel] to live up to their commitments as defined in the road map." State Department Spokesman Richard Boucher said Tuesday after a meeting between Israeli and American officials in Washington.