It once was a truism that only Prime Minister Menachem Begin, With his credentials as a genuine Jewish nationalist, could have led Israel out of Sinai.
The Egyptians, who benefited from Mr. Begin's then-commanding position in Israel politics, may realize now that he no longer has the authority to forfeit control of the occupied West Bank and Gaza Strip in favor of Palestinian autonomy.
That may be one of Egypt's considerations in putting off the long overdue negotiating sesssion that was to have opened Aug. 4 in Alexandria, Egypt. Passage of the Jerusalem law by the Israeli Knesset (parliament) was the over excuse, but Egyptian diplomats based in Tel Aviv undoubtedly have advised President Anwar Sadat by now that Mr. Begin's days as prime ministers may, indeed, be numbered and that he therefore cannot show flexibility in the three-sided talks among Egyptian, Israeli, and United States diplomats.
President Sadat, therefore, may have found the controversial Jerusalem statute useful as an obstacle to the resumption of autonomy talks. The statute defines the city in toto, including its Arab-populated former Jordanian sector (now comprising new Jewis housing estates as well), as the "eternal capital" of Israel.
The Egyptian leader sent an urgent letter to Mr. Begin, hand-carried and delivered by his suave Ambassador to Israel, Saad Eddin Mortada, objecting to the unilateral definition of Jerusalem's status. But well-informed quarters here indicated that the letter's tone was neither unfriendly nor irreconcilable.
Thie left the remainings members of the Begin Cabinet, depleted most recently by the resignation of another of its most gifted membes, ex-Justice Minister Shmuel Tamir, to devote a special meeting to the formulation of a suitable reply.
Assuming an appropriate approach can be found by the ministerial committee signed to completing the task, and that President Sadat is satisfied with the official Israeli explanations, a new date could be designated for the suspended autonomy conclave. But that would be possible only by minimizing the practical consequences of the Knesset action and leaving some major aspects of Jerusalem's situation open to trilateral discussion.
These assumptions are made in the light of the Tamir resignation, a surprise development that has produced Mr. Begin's parliamentary majority to the very minimum: one or two votes, depending on one's basis of political calculation.
Mr. Tamir, a brilliant trial lawyer and consummate politician, is pledged to support the ruling Likud coalition in his capacity as a Democratic Movement member of the Knesset. But he hinted that his views may diverge from those of the government at times. The resignation was caused by the sudden withdrawal of one of Mr. Tamir's former (and possibly current) cronies, Knesset deputy Akiva Nof, from the Democratic Movement's parliamentary faction. This left the Democrats with as many Cabinet ministers as Knesset deputies, an absurd state of affairs in Mr. Tamir's opinion. And since Social Welfare Minister Israel Katz apparently was averse to quitting, Mr. Tamir decided to step down instead.