Former U.S. senator John Marshall Butler (R-Md.), 80, who won his seat in 1950 in one of the most controversial campaigns in the nation's electoral history, died Tuesday after a heart attack.

Sen. Butler, a conservative who served two terms, died in North Carolina after collapsing at a hotel where he and his wife had stopped while returning from vacation in Georgia.

A Baltimore native, Sen. Butler had never held elective office before defeating veteran Democrat Millard E. Tydings in a campaign that involved a composite photo of Tydings and a Communist leader and led to a Senate investigation.

The campaign was notable for the particularly vivid fashion in which it reflected the issues and charges that inflamed and divided the nation during the outbreak of the Kerean war and the prominence of the late senator Joseph RR. McCarthy (R-Wis.)

Tydings had headed a subbcommittee that investigated McCarthy's charges that the State Department was ridled with subversives. Tydings found for what the Wisconsin senator called a "whitewash."

This set the stage for the 1950 election in which Sen. Butler, a lawyers, set out to exploit what Republican strategists saw as grass-roots disapproval of subversives at home and aggressors abroad.

Campaign workers for Butler circulated a tabloid with a composite picture that by some descriptions appeared to show Tydings listening intently to Communist leader Earl Browder.

Tydings cited the picture in his complaint to the Senate after his defeat. A Democratic-dominated Senate committee later criticized tactics used in the campaign, but no action ever was taken against Sen. Butler.

After the release of the committee report, Sen. Butler said he believed the picture was designed to illustrate the "attitude" shown by Tydings when Browder testified in 1950 before Tydings' committee. Anything else read into the picture "is a matter of imagination," Sen. Butler said.

Analysts of the 1950 campaign also noted that Sen Butler possessed the assets of a matinee idol appearance and a quick friendliness that impressed many voters.

A former newsboy who had worked at age 14 in a mattress factory for $3 a week, Sen. Butler described his career as a Horatio Alger story.

After 26 months of military service during World War I, he went to night school, then enrolled in Johns Hopkins University, where he was a star right tackle on the football team. He dropped out to work in his father's real estate business but attended night school and obtained a law degree.

After emerging from obscurity to upset Tydings by 43,000 votes in 1950, Sen. Butler handily won reelection in 1956 by defeating George P. Mahoney, for years a perennial campaigner. He did not seek reelection in 1962, and was succeeded by Daniel B. Brewster.

In Congress, Sen. Butler was known for his support of the Merchant Marine, Baltimore harbor and a strong national defense.

In addition to his wife, Mary Louise, survivors include two sons, John Marshall Jr., and Edwin F. Abell, and a daughter, Maria Harrington.