JERUSALEM (JTA) - A six-month cease-fire between Israel and Hamas, which was due to go into effect yesterday (Thursday), could help create conditions for wider peacemaking between Israel and the Palestinians.

But there are two huge potential stumbling blocks: Israeli generals doubt whether the "tahadiyeh," or truce, will hold, and the chances that Hamas and the more moderate Fatah, which controls theWest Bank, will work in tandem for a wider peace deal are remote.

Egyptian mediators earlier in the week reported that the cease-fire it had been brokering was a done-deal. Israeli forces will stop initiating attacks in Gaza and Hamas will ensure an end to cross-border shelling from the territory, the mediators said.

Israeli officials earlier said that in addition to a suspension of hostilities, it would involve easing a blockade on Gaza.

But Israel also has demanded progress in talks on the release of Gilad Shalit, a soldier held hostage by Hamas, for Gaza's border crossing with Egypt to open.

When Hamas violently took control of the Gaza Strip a year ago, Israeli and American leaders saw a window of opportunity for peacemaking with the relatively moderate Fatah leaders.

The idea was that with Hamas out of the way, Palestinian Authority President Mahmoud Abbas finally could negotiate the two-state deal Israel and the Palestinians have been trying to close ever since the signing of the 1993 Oslo Accords.

A year later, the situation is more complicated.

Abbas hasn't had the authority or power to deliver on a deal that would include only the West Bank, let alone a full-fledged peace-abiding Palestinian state in theWest Bank and Gaza.

After some 2,000 Kassam rockets and mortar shells blasting Israel's southern towns, it has become clear that as long as Hamas controls Gaza, it can scuttle any deal by rocketing Israeli civilians.

For weeks, Egypt has been mediating a temporary lull in hostilities between Israel and Hamas. In a breakthrough last weekend, both sides agreed to make major concessions. Hamas dropped its insistence on linkage between a cease-fire in Gaza and one in the West Bank, and Israel gave up its demand for Shalit's release as part of an initial ceasefire deal.

Hamas' compromise on the West Bank, where Israel insists on freedom of action against radical militants, constitutes a major retreat. The implication is that Hamas does not speak for the Palestinian people as a whole but only for Gaza.

Israel agreed to decouple the cease-fire and Shalit's release on the understanding that immediately after the lull takes hold, the parties will begin intensive negotiations through Egypt on a prisoner exchange.

Although neither recognizes the other, Israel and Hamas for their own reasons have agreed to stop shooting after a year of relentless hostilities. Both sides have much to gain from the cease-fire.

Over the past few months, Hamas and other militant groups have been taking a pounding from the Israel Defense Forces, losing an average of four members a day. That pounding continued Tuesday, even as the cease-fire was announced.

Moreover, without a ceasefire, Hamas leaders know they face the prospect of a major Israeli ground incursion that could deal a crushing blow to their military infrastructure.

They also hope that if the lull holds, Israel will lift its economic blockade and open border crossing points, including the Rafah crossing into Egypt.

For Israel, a cease-fire would enable it to avoid the inevitable casualties of a major ground operation, ensure quiet for civilians in the Gaza perimeter who have been under constant rocket attack for more than seven years and create conditions for Shalit's release.

Hamas attacks in recent weeks have become more intense after the militiamen received Iranian 120mm mortars, which are more accurate, more deadly and have a longer range than the homemade Kassam rockets they had been using.

Israel, however, does have some major concerns.

Israelis are worried that Hamas will use the lull to bring in heavy weapons, build bunkers, move up forces and lay mines close to the border fence. In short, Hamas will be able to make major strides toward what the Israelis call the "Hezbollization of Gaza" - the creation of a military infrastructure similar to that of the Iranian-backed Hezbollah in Lebanon.