Overruling White House worry that Israel's right-wing government wants only more delay, not peace, Secretary of State James A. Baker III is gambling on help from American Jewish leaders to persuade the new Likud regime to get serious on talks with Palestinians.

Jewish leaders here, alarmed by signs of diminishing U.S. support for Israel, are sending a stream of warnings, including one from Democratic Sen. Joseph Lieberman (D-Conn.), the first Orthodox Jew ever elected to the Senate. In Jerusalem the other day, the senator said the $3 billion annual U.S. aid is not sacrosanct and, given budget wars and the fact that Israel no longer has an ''enthusiastic majority'' in Congress, may be cut.

Baker's key Mideast diplomats, who are in constant touch with leading American Jews, say privately that warnings like Lieberman's may be influencing an Israeli leader unknown in the West but crucial to Baker's plan for Palestinian elections: Foreign Minister David Levy, the first chief diplomat in Israeli history unable to speak English.

When Levy's boss, Prime Minister Yitzhak Shamir, wrote President Bush in June about Palestinian peace, the White House read his words as a death sentence for the Baker plan. But Baker's diplomats, inveterate optimists, saw a glimmer of light. ''The prime minister clearly does not want to close the door,'' one of them told us.

With that conclusion, Baker persuaded the White House to make one more attempt to resurrect the Baker plan, which calls for talks with a broad range of Palestinians, including some who have obvious links to Yasser Arafat's Palestine Liberation Organization. When Levy comes here for the first time on Aug. 9, he will get a warm reception but a cold warning: We'll talk if you're serious.

If President Bush and Baker decide Levy is diddling or cannot deliver without breaking up the far-right government, the United States will move on to a series of new peace efforts, including one whose likely highlight will be talks between Washington and such Arab leaders as Syria's President Hafez Assad. But Baker believes he has a shot.

His gamble to get Levy's attention fits in with pressures from American Jewish leaders who have been beating a path from Bush's Oval Office to Baker's State Department to Shamir's office near the Israeli Knesset. Henry Siegman, executive director of the American Jewish Congress -- a pillar of Jewish sentiment in this country -- got heavy notice in The Jerusalem Post, which quoted him as saying that another American Jewish organization was "reckless and irresponsible" for not telling Shamir that the U.S.-Israeli relationship ''is in the process of being undone.''

His target was Seymour Reich, current chairman of the Conference of Presidents of Major Jewish Organizations -- a group with automatic access to the White House, State Department and Shamir. Siegman complained that Reich and some other Jewish leaders are afraid that if they tell Shamir the truth about Israel's decline in the United States, they will be barred from his office.

Reich denied to us that he has played such games and said that Siegman claims he was misquoted. Reich agreed, however, that he has no dispute with Theodore R. Mann, a past chairman of the Conference of Presidents, who wrote to Baker on June 8 praising the U.S.-PLO dialogue that is anathema to Israel's Likud leadership.

Mann's letter said that of course the United States must insist on Arafat's denunciation of the aborted raid by the PLO's Abul Abbas against the Tel Aviv beaches and persuade Arafat to discipline such terrorists. But the U.S.-PLO talks, he said, have ''proved to be a valuable channel ... to advance the peace process'' and should be re-started as soon as possible. Reich told us: ''I agree with Ted Mann on that.''

Reich, Mann and Siegman are only the visible sliver of an iceberg of Jewish opinion here that Baker's men at State hope is chilling orthodox Likudnik politicians like David Levy -- and even Yitzhak Shamir. Shamir's statement last week to Yoel Markus, Ha'aretz's eminent columnist, was unexpected. The prime minister, who compares Arafat to the devil, said he would have no objection if Palestinian negotiators consult with the PLO during talks with Israel -- so long as the PLO does not try ''to run the whole thing.''

Baker will discover soon enough whether that represents a new voice of reason by the famed old Jewish freedom-fighter, a terrorist himself in the war of independence. If Shamir has listened to his Jewish friends here as intently as they have been speaking, the optimists at State may look shrewder than the skeptics in the White House.