With an agreement on an agenda for talks on the withdrawal of Israelis (and other outside occupiers) from Lebanon, the bargaining on a final agreement has barely begun. The Reagan "initiative" for a solution of the wider Arab-Israeli conflict is stalled; the Israelis are proceeding apace to foreclose the outcome by fastening their grip ever more tightly on the West Bank; and the faint flowering of interest among the "moderate" Arabs is in danger of withering.

Meanwhile, the United States is moving inexorably toward a presidential election year, when the sensitivity of anything having to do with Israel begins to work against productive American diplomacy. Time is running out. But time, at various points along the many years of Middle East crisis, is always running out--with differing but often disastrous results.

So what else is new?

President Hosni Mubarak of Egypt will be bringing some interesting answers with him when he arrives here this week for a meeting with President Reagan. One thing that's new, according to Egyptian officials involved in the preparations, is that, by contrast with their first encounter nearly a year ago, the two men see the problems in roughly the same way.

Not that Mubarak entirely accepts the Reagan view of how the "peace process" should wind up. But the two are very nearly in accord on how--and how rapidly--it must proceed.

Item: For roughly the same reasons, Mubarak and Reagan give absolute priority to Lebanon. The Reagan administration recognizes that nothing constructive can be done about the larger issues of West Bank "autonomy" and Palestinian rights until there has been an agreement on at least a timetable for Israeli withdrawal from Lebanon, and perhaps the beginnings of an actual pullback.

The Egyptians put it a little differently. That much progress on Lebanon, they argue, is a precondition to progress on the larger issues because nothing less would give "moderate" Arabs confidence that the United States has any influence on Israel. "If you can't budge Israel from Lebanon, where it has no claim to be," an Egyptian official argues, "it would be the worst advertisement of your capabilities in the much tougher problem of the West Bank."

Item: By Egyptian calculations, out of their own experience, Ronald Reagan has moved a long way from the Middle East approach he took when he first met Mubarak a year ago. Those were the days of Alexander Haig's "strategic consensus," when the Soviet menace was everything, the Palestinian problem seemed minor, and Reagan's command of the whole subject was in what might be called the "cue-card stage."

As the Egyptians trace it, the Reagan approach had already moved appreciably closer to that of the Egyptians just prior to the Israeli invasion of Lebanon last June, when the Reagan administration was just beginning to tackle the Palestinian question. But the Lebanese war, in Arab eyes, showed the United States, at worst, as Israel's co-conspirator and, at best, either indifferent or impotent.

Then came Reagan's peace plan, in his famous Sept. 1 speech, and U.S. prestige rose substantially. Israel's rough rejection of the plan was a setback. Still more so was the slaughter at the Sabra and Shatila refugee camps. The campaign to win over Jordan's King Hussein and the Palestinians has been a confidence-rebuilder, as has the recent demonstrable evidence that the United States is pressing the Israelis hard on the Lebanese negotiations.

But the real test of U.S. influence and reliability in the eyes of the Egyptians and others --a further rise or another fall of this roller coaster--will now be the rate of progress in the Lebanese talks.

Mubarak would apply a second test--for Egypt's sake. His own security internally, his relations with the "moderates" (Jordan, the Gulf States, Morocco), and his ability to carry weight in the region would all be nicely enhanced by a little more military and economic aid from the United States. He would like to receive at least as much U.S. support as Israel, which is, after all, one-tenth Egypt's size.

Even here, however, there is a common denominator with the rest of what Mubarak would like to convey. The Egyptians see themselves slowly reacquiring their lost leadership role in the Arab world. They see a large part of the Arab world naturally inclined to place its faith in the United States. But they also argue that almost all of the "moderates" confront a threat from within and without at the hands of religious extremists, readily exploited by the Soviets. The radical elements are well positioned to stir up trouble for governments, as one Egyptian puts it, "whose reliance on the United States has brought them no benefits."

For Mubarak, the problem is especially acute. Having been made a pariah among the Arabs for making peace with Israel, Egypt is under all the more pressure--after the Lebanese war--to demonstrate the wisdom of throwing in its lot with the United States. There is increasing evidence, in the U.S. approach to the negotiations over Lebanon, that Ronald Reagan sees Hosni Mubarak's point.