Clark MacGregor, a former Republican congressman from Minnesota who led President Richard M. Nixon's re-election campaign in 1972 and remained unscathed by the Watergate scandal that forced Nixon's resignation two years later, died on Monday at a hospital in Pompano Beach, Fla. He was 80 and lived in Washington.

At Nixon's invitation, Mr. MacGregor joined the White House staff in 1971, a year after he left the House, to manage its Congressional liaison operations. He was doing that in June 1972 when burglars broke into the offices of the Democratic National Committee in the Watergate apartment complex in Washington. The break-in set off a chain of events that would implicate the White House in domestic spying, illegal fund-raising and a cover-up conspiracy that led to criminal charges against more than two dozen administration or campaign officials and contributors.

In July, a month after the break-in, Mr. MacGregor was named chairman of the Committee to Re-elect the President when John N. Mitchell, Nixon's former attorney general and one of the most powerful men in Washington, abruptly resigned, saying he had to spend more time with his family. In 1975 Mr. Mitchell was convicted of obstruction of justice, conspiracy and perjury, and he spent 19 months in federal prison.

Mr. MacGregor, a mainstream Republican with a spotless record, was a logical choice to take over the campaign. He steadied the committee even as the Watergate affair grew into a national scandal. He took charge of major elements like strategy and fund-raising, was never tainted by the swirling accusations and revelations, and led his team to resounding victory over the Democratic challenger, Senator George McGovern of South Dakota.

Throughout, Mr. MacGregor gamely deflected the reports of impropriety or worse, accusing the news media of trading in left-wing innuendo and character assassination.

After arrests and court proceedings in the case in 1973, he stated that he, too, had been misled and lied to by White House and campaign aides. He left politics for good.

Clark MacGregor was born in Minneapolis and graduated cum laude from Dartmouth College in 1946 and from University of Minnesota Law School two years later. During Army service in World War II, he was attached to the Office of Strategic Services, the forerunner of the Central Intelligence Agency, and won a field commission as a second lieutenant in Burma, along with a Bronze Star and the Legion of Merit.

He practiced law in Minneapolis until his election to Congress. He represented the Third Congressional District in suburban Minneapolis for eight years, through 1970, serving on the judiciary and banking and currency committees. He did not seek re-election that year but instead ran as the Republican nominee for the Senate, accepting the challenge when the Democratic incumbent, Senator Eugene J. McCarthy, decided not to defend his seat. In his place, former Vice President Hubert H. Humphrey joined the fray and soundly defeated Mr. MacGregor.

Mr. MacGregor earned a reputation as a middle-of-the-road Republican with strong civil rights credentials, who enjoyed the trust of both fellow members and journalists on Capitol Hill.

After he returned to private life, he became senior vice president for external affairs at the United Technologies Corporation, serving as its chief aeronautics lobbyist in Washington until his retirement in 1987.

He was not known to have maintained a personal relationship with Nixon after the 1972 campaign. But he was a regular in Washington social circles and served on the boards of the National Symphony Orchestra and the Wolf Trap Foundation.

Mr. MacGregor is survived by his wife of 54 years, Barbara Spicer MacGregor; three daughters, Susan Wheelwright of Boston, Laurie MacGregor of Hanover, N.H., and Eleanor MacGregor of Kensington, Md.; and eight grandchildren.

Clark Macgregor (1922)