Faced with a tight timetable, restlessness among the members and a string of Cabinet-level witnesses, the congressional Iran-contra panels changed the format of their last two weeks of public hearings and in the process turned the sessions from fact-finding into a rush to adjournment, according to committee members and staff.

After testimony of former national security adviser John M. Poindexter, Republicans and Democrats had a "mutual motivation" to terminate the hearings as soon as possible, Rep. Jim Courter (R-N.J.) said. "The big story was out and they {the committees} didn't want to follow it with a witch hunt. Republicans wanted to get out as quickly as they could and the Democrats were worried that the worm could turn."

The "big story" he referred to was Rear Adm. Poindexter's July 15 disclosure that he never told President Reagan of the plan to divert proceeds of U.S.-Iran arms sales to support the contras fighting in Nicaragua.

When Poindexter concluded his testimony on July 21, the committees used appearances of the top administration officials mainly to attack the credibility of Poindexter and former White House aide Oliver L. North, and buttress a theme that committee sources said was acceptable to Democrats and Republicans: that those two National Security Council officials were at the heart of a "secret government," or "junta," that operated inside the White House.

The Cabinet witnesses defended Reagan and stressed that he had been ill-served or misled by his NSC staff. That theme was echoed in closing statements of the four committee leaders Monday, reflecting determination of the two Democratic chairmen, Sen. Daniel K. Inouye (Hawaii) and Rep. Lee H. Hamilton (Ind.), to maintain a bipartisan investigation.

Inouye has said that he sought to conduct the congressional investigation in a bipartisan fashion because he believed at the outset that the president would be hurt by the probe.

After Poindexter's testimony, the committees also curtailed the role of their counsels in questioning the final four Cabinet-level witnesses: Secretary of State George P. Shultz, Attorney General Edwin Meese III, former White House chief of staff Donald T. Regan and Secretary of Defense Caspar W. Weinberger.

There was also agreement that "if members of the Cabinet were going to be confronted, it should be done by senators and congressmen, not the staff," said a committee aide. House Counsel John W. Nields Jr. was allotted two hours to interrogate Meese, and took three. The questioning of Weinberger by House counsel Neil Eggleston lasted only one hour.

Senate Counsel Terry A. Smiljanich rushed through his interrogation of Regan. For example, he asked about only one page of Regan's 30 pages of handwritten notes of a crucial Nov. 10, 1986, meeting of Reagan and top advisers. He also skimmed over another exhibit, the entries for 21 days of morning national security briefings of the president, which Regan regularly attended.

Earlier in the investigation, committee leaders said privately that the testimony of Poindexter and Lt. Col. North would be used in part to establish a chain of accountability for the Iran-contra affair up the line, wherever the evidence took them. That presumed that the interrogation of top officials would be as thorough as the questioning of lower-ranking witnesses.

But the rigid time constraints and size of the committees -- 26 members -- made that increasingly difficult as they approached their self-imposed Aug. 7 deadline for concluding public hearings.

Rep. Ed Jenkins (D-Ga.) blamed this rush to adjournment on the House and Senate as a whole, which directed that the hearings be wound up and a report issued by October. "The House of Representatives made a mistake in placing a time limit on the committee," Jenkins said, adding that the time pressures made it difficult to prepare for new witnesses or follow leads turned up by questioning.

Poindexter's testimony is seen as the turning point by both Republicans and Democrats.

On May 2, during the first day of his private depositions with the committee, Poindexter testified that he never told Reagan about the diversion. That was three days before the committee began its public hearings, but Poindexter's story was known only to the four committee leaders and their counsels, and had been sealed under an agreement with independent counsel Lawrence E. Walsh.

Meanwhile, many committee members, as well as journalists, assumed on the basis of North's testimony that Poindexter would suggest in some way that Reagan had indirect, if not direct, knowledge of the diversion scheme. North had testified that he had been assured by Poindexter that Reagan approved of the diversion.

Jenkins, one of four questioners of North, said he was "surprised" when he read the Poindexter deposition just before his public testimony.

"A lot of the members felt that was it," said an aide to a Senate committee member. "Many of them backed off."

At the same time, criticism of the system of Rep. Ed Jenkins (D-Ga.) blamed this rush to adjournment on the House and Senate as a whole, which directed that the hearings be wound up and a report issued by October.

having staff lawyers conduct extensive questioning of witnesses came to a head.

Sen. Warren B. Rudman (R-N.H.) said the committees earlier had contemplated "compressing" questioning by counsels. But this was difficult to do with witnesses such as retired Air Force major general Richard V. Secord and his business partner Albert A. Hakim, whose information was so complicated that it took specialists to unravel.

Dissatisfaction with prolonged questioning by the staff boiled up after Nields used two full days interrogating North. Even Senate Democrats who favored tough questioning by counsel complained privately that "Arthur got more in 2 1/2 hours than John got in two days."

"Arthur" referred to Senate Counsel Arthur L. Liman. However, Liman was also the subject of criticism, this time in public before the committees, when Republican members challenged a statement he had made to reporters questioning Poindexter's credibility.

Courter said yesterday that committee members had been led to believe that committee lawyers would concentrate on eliciting the factual "story" from witnesses, but members would do the cross-examination. Instead, he said, counsels did "the direct, cross and redirect," and committee members were left with just 10 minutes.

One of the first committee members to complain publicly was Sen. David L. Boren (D-Okla.) who, at the end of the third day of staff questioning of North, said he believed committee members could have done a better job. In the final phase, however, Boren asked no questions of Weinberger or Meese. He asked two questions of Shultz, but also said that the testimony made him want to "stand up and cheer."

Some members did press the final four witnesses, both to establish their responsibility for the Iran-contra affair and to learn more about the president's knowledge and involvement.

One example was Sen. George J. Mitchell (D-Maine), who drew from Shultz an acknowledgment that Reagan had not informed him that he had signed a written authorization for the 1986 U.S. arms sales to Iran. Sen. Sam Nunn (D-Ga.) pressed Regan about the president's apparent misconception that Iran was losing the war with Iraq, a view used by the president to justify selling arms to Tehran.

One Democratic aide praised Sen. William S. Cohen (R-Maine) as a "Republican who would go wherever the truth took him." Alone among the members, Sen. James A. McClure (R-Idaho) continued to press for answers about the Israeli role in the Iran initiative up to the final witness.

Illustrating the obstacles faced by the committees was the refusal by an executive branch review group at the White House to declassify a Nov. 21, 1986, State Department memorandum sought by McClure. The memo reportedly makes reference to Israeli arms transactions with Iran before the 1985 transactions undertaken with U.S. government knowledge.

A senior member of the Senate staff said there had been generally good cooperation with the White House and agencies in obtaining documents, and obtaining release of classified documents. But some House investigators complained that documents often were provided at the last minute, and some nonclassified documents had been blacked out or omitted.