When he returns Friday, from his talks with President Carter, Israel Prime Minister Menachem Begin will come under intense political pressure stemming from the dispute about the legal status of Jewish settlements in the West Bank and Gaza Strip.

Some factions of Begin's ruling Likud coalition are pressing for a law that would shield the settlements from any conceivable international or domestic legal assault. Demonstrations aimed at forcing the Cabinet to draft such a law are planned for next week.

But on the other hand, so many ministers and legislators are opposed to such a measure that they could bring down the government and force new elections if Begin pushes ahead with it.

Defense Minister Ezer Weizman, a member of Begin's own Herut Party, added his voice to calls for a change in the government by saying an atmosphere of "malaise" in Israel requires early elections.

Interviewed on a television talk show, Weizman said that because of its failures, the government should "go to the voters to ask for a verdict." He predicted new balloting within six months.

Weizman's remarks created an uproar in the Likud, with Herut Knesset member Dov Shilansky calling for the defense minister's resignation. Opposition Labor Party leader Shimon Peres called the Weizman statement a "patriotic" act, and a new opposition group, called "Elections Now," immediately asked Weizman to become its chairman.

Against the advice of the attorney general, the prime minister has promised the leaders of Israel's ultranationalist settlement movement, Gush Emunim, that he will raise the controversial proposed settlement law at the first Cabinet session after his return from Washington.

As if to remind Begin of his word, about 60 settlers from the West Bank have been conducting a hunger strike on a grassy knoll overlooking the Knesset (parliament) not only immediate adoption of a settlements protection bill, but an intensified government program of expropriating land to expand the outposts. Today, the 29th day of their fast, strikers vowed to force a coalition crisis if their demands are note met.

The key factor in the dispute is the National Religious Party which, with 12 Knesset members, is the pivotal partner in Begin's fragile Likud coalition.

Several key NRP Knesset members, including Interior Minister Yosef Burg and NRP legislative faction chairman David Glass, have already suggested publicly that the time may be ripe for new elections, and the settlements status bill is seen by an increasing number of influential politicans as the issue that could catalyze a coalition crisis.

If even just five of the NRP Knesset members of the 120-member parliament leave the government -- or fewer if they are joined by equally disgruntled members of the centrist Democratic Movement party -- Begin would be forced to resign. Numerous public opinion polls indicate that the opposition labor party would win any new election by such an overwhelming margin that Israel would have a majority party in power for the first time in its history.

At the center of the controversy is a proposed law that would empower the Cabinet to approve settlements for any reason -- even those motivated by nothing more than a claim of Biblical right to the West Bank -- and which would prevent Israel's High Court of Justice from enjoining the government from building new outposts.

Last year, the court ordered the dismantling of the controversial Elon Moreh settlement near the West Bank Arab city of Nablus, saying the government had failed to prove that the outpost was necessary for security reasons.

The settlements protection bill would reach beyond the High Court and, in effect, neutralize several Hague convention articles which prohibit the expropriation of occupied territory except for compelling military purposes. In their landmark Elon Moreh decision, the High Court justices cited the Hague and Geneva conventions and said the outpost was not needed for military reasons.

The proposed law would also, in effect, declare the West Bank and Gaza as not falling within the definition of "occupied land," a position Israel long has held, preferring to use the term "administered territory." Israel holds that Jordan annexed the West Bank illegally in 1948 after capturing it in the preindependence fighting, and that the legal status of the territory has never been resolved.

Even though Attorney General Yitzhak Shamir has disassociated himself from the proposed bill, saying it would have grave domestic and international consequences, Begin appears determined to bring it to the Cabinet. Israel has no constitution, so that although the measure would seem to hamstring the nation's highest court, it is not on the face of it unconstitutional.

If the measure were adopted by the Cabinet, which is far from assured, it would result in a deep division within the NRP that would be reflected in the Knesset and possibly lead to defections of NRP doves, who are anxious anyway to start associating the party with the Labor Party in the next government.