David M. Abshire, who led respected research groups and held high government posts but made his most visible mark by helping President Ronald Reagan navigate the political storms of the Iran-contra scandal, died on Friday in Alexandria, Va. He was 88.

His death was announced by the Center for the Study of the Presidency & Congress, a Washington group he helped lead.

Reagan sought out Mr. Abshire in December 1986. He called him in Brussels, where he was the United States ambassador to NATO, and asked him to accept a cabinet-level job as coordinator of the White House’s response to multiple investigations of the administration’s secret sales of arms to Iran, despite an embargo on such sales.

There were allegations that United States officials had hoped the arms sales would secure the release of several hostages being held in Lebanon by a group with ties to Iran, which would have been another violation of policy. Proceeds from the sales were to be used to finance the anti-Communist insurgents in Nicaragua known as contras — aid that Congress had expressly forbidden.

Reagan asked Mr. Abshire to handle all requests and obligations stemming from investigations in both the House and the Senate and from an independent commission headed by John Tower, a former senator from Texas.

“What we wanted was someone who would come and could immerse himself in all the details of this Iran controversy — the dates, when the arms went, who said what on which date,” Patrick J. Buchanan, then the White House communications director, said in an interview with CNN in 1986. “It really is a detailed job, and the rest of the White House staff, which was not involved in the controversy, has to get on with the budget, has got to get on with the State of the Union. We simply don’t have the expertise.”

In a profile in 1987, The New York Times said the job could leave Mr. Abshire in a “potentially tricky position” and raised the possibility that he could turn up an incriminating “smoking gun.”

Mr. Abshire accepted the post on the condition that the administration would be forthcoming. He told The Times that he regretted suppressing information about military incursions into Laos and Cambodia during the Nixon administration, when he was assistant secretary of state for congressional relations.

“That,” he said, “was an example of how not to do it.”

In his first meeting with Reagan, recounted in his 2005 book, “Saving the Reagan Presidency: Trust Is the Coin of the Realm,” Mr. Abshire told the president that it was unwise to keep insisting that the United States did not trade arms for hostages. He pointed out that two-thirds of the public believed that the administration had made such a deal.

“Dave, I don’t care if I’m the only person in America that does not believe it — I don’t believe it was arms for hostages,” he quoted Reagan as saying.

But in a dozen meetings with the president and in others with the first lady, Nancy Reagan, Mr. Abshire pressed his case for admitting what seemed obvious to him and to many others. He also released thousands of unedited documents to investigators, handled press relations and signed off on the president’s speeches about the subject.

On March 4, 1987, with evidence of the arms deal mounting, Reagan admitted in a speech to the nation that he had learned he was wrong. “What began as a strategic opening to Iran deteriorated, in its implementation, into trading arms for hostages,” he said.

Mr. Abshire soon resigned, feeling he had finished the job 90 days after taking it. Reagan largely escaped personal blame and saw his approval rating rise from 46 percent to 64 percent in less than two years.

The Washington Post in 2006 called Mr. Abshire the “judicious convener and manager of the A-list powerful.” In 1962, he joined with Adm. Arleigh Burke to start the Center for Strategic and International Studies, originally as an affiliate of Georgetown University. Distinguished foreign policy figures like Henry A. Kissinger, James R. Schlesinger, Zbigniew Brzezinski and Brent Scowcroft have been senior advisers and adjunct fellows there.

Mr. Kissinger, at a colloquium in Mr. Abshire’s honor in 2006, said that Mr. Abshire had a knack for getting people to do what he wanted, “making you feel that he’s doing you a tremendous favor for giving you that opportunity.”

From 1999 to 2012, Mr. Abshire was president and chief executive of the Center for the Study of the Presidency & Congress. More recently he was vice chairman. He served on government task forces and policy study groups and wrote seven books. He headed Reagan’s foreign affairs transition team after his election in 1980, and was often mentioned as a candidate for national security adviser in Republican administrations.

His job as assistant secretary of state under President Richard M. Nixon was to be a liaison to Congress. Nixon then appointed him chairman of the Board for International Broadcasting, overseeing Radio Free Europe and Radio Liberty.

As NATO ambassador, Mr. Abshire helped parlay the deployment of American Pershing II missiles in Europe into a treaty limiting intermediate-range nuclear weapons there.

David Manker Abshire was born in Chattanooga, Tenn., on April 11, 1926. An imposing figure at 6-foot-4, he never lost his courtly Tennessee drawl.

He graduated from the United States Military Academy at West Point in 1951 and, as a platoon leader in the Korean War, was awarded a Bronze Star and other decorations for bravery. He earned a Ph.D. in history from Georgetown.

Mr. Abshire, who died in a nursing home in Alexandria, is survived by his wife of 56 years, the former Carolyn Sample; his son, Lupton; his daughters, Anna Bowman, Mary Lee Jensvold, Phyllis d’Hoop and Carolyn Hall; and 11 grandchildren.

Reagan was not the first president to ask for Mr. Abshire’s help in dealing with a crisis. In his memoir, Mr. Abshire wrote that Nixon had asked him to join his staff to fight the threat of impeachment during the investigations of the cover-up of the Watergate break-in. He tactfully said no.

He recalled that when a relative expressed amazement that he had turned down a president, he replied: “I don’t believe he’s telling the truth.”

Correction: Nov. 7, 2014

Because of an editing error, an obituary on Tuesday about David M. Abshire, who coordinated the Reagan administration’s response to investigations of the Iran-contra scandal, misidentified the country in which hostages at the center of that scandal were held. It is Lebanon, not Iran.