President Carter's embarrassing verbal stumbles in trying to please all sides in the politics of Mideast peacemaking brought an anguished, though private, cry for help from a prominent Democrat to White House counsel Robert Lipshutz.

At a recent small luncheon, this Democrat complained that Carter's crashing through verbal thickets with one explosive word contradicting another left everyone in the dark as to what U.S. policy really is. Unplanned ambiguity, he said, must cease.

The answer helps explain presidential contortions that swithched the President's freign trip to Egypt at mid-course and generates worry about the future. This is LIpshutz's reply: Jimmy Carter is contemptuous of Richard Nixon's careful formulations and insists that his own free-wheeling talk works better.

The President really means it when he says he wants "an open administration," Lipshutz told his luncheon guests. He's going to continue that way; Nixon never said a word that wasn't weighed and tested; there was no such thing as spontaneity in the formulations of his foreign policy; Jimmy is different; he speaks freely, and he speaks his mind.

Even if "spontaneity" and the drive to be different from Nixon - not sheer clumsiness - truly explain the President's verbal pratfalls, that does not mitigate the consternation his repeated mistakes have caused in Mideast capitals. His year end television interview Dec. 28, on the eve of his world trip, was the most recent case in point.

What was so "embarassing" to President Sadat was not Carter's often-stated opposition to an independent Palestinian state. It was the thorny off-shoot of a new thought: These stateless Palestinian residents under Israeli military control might decide "to be . . . Israeli citizens . . . to actually run for the Knesset [the Israeli Parliament]."

Such a thought in the real world of Mideast politics was appalling to Sadat and Arab leaders everywhere, revealing presidential misconception of reality never evidenced before.

In his early "homeland" formulation - delivered without forethought in Clinton, Mass., last March 21 - Carter spoke feelingly: "There has to be a homeland provided for the Palestinian refugees who have suffered for many, many years." No mention there of Palestinians as wards of Israel.

Likewise, when asked at his April 8 press conference, just after Sadat's visit here, if there should be "Jordanian control" of the Palestinian homeland, Carter jockeyed: "That's a question that I wouldn't want to answer for President Sadat. I will let him make his own statements publicly and I don't intend to repeat what he tells me privately." That had the ring of a good, solid answer.

By July 12, however, Carter seemed to be feeling presure from Israel. Asked again about the "homeland," he said his "preference" was for the "entity" that "should be tied in with Jordan and not be independent."

Besides fumbling the "homeland" question on several occasions, Carter also has shown singular lack of follow-through on the question of Israeli settlements in occupied Arab territory.

Shortly after Israeli Prime Minister Menahem Begin's trip here in July, the President said he had "let [Begin] know very strongly" that any new settlements would cause the United States "deep concern."

But a bit later, on Aug. 5, after Begin continued to approve new settlements and legalize old ones, Carter told reporters: "I think what he did was in consonance with the desires of the Israeli people." That introduced a new factor in the settlement equation that was manna to Israelis hungry for a show of American sympathy, but it was an unexpected blow to the Arabs.

There has been no presidential response yet to the Israeli decision last week to send new settlers to the occupied Egyptian Sinai. Considering the ups and downs of Carter's Mideast verbalisms, that should cause no surprise.

In sum, Carter's loose lip on issues of life and death to Jews and Arabs of the Mideast have caused anguish to many parties, including some of the President's most stalwart American supporters. So far, there has been no mortal damage to his overall drive for a peaceful settlement, which he has pursued with more intensity than his predecessors in the White House.

What is needed now is less hip-shooting and less effort to contrast Jimmy Carter to Richard Nixon. That is why, when he gave the results of his 45-minute talk with Sadat last Wednesday to resolve his self-created emergency, his decision to read a rare written statement brought sighs of relief. In at least this one case, the ambiguity necessary for both sides was careful and intentional. After all the amateurish impromptu diplomacy, it could be a sign of creeping professionalism.