On February 26, 1964, a bathroom rug slipped under him in his Columbus, Ohio, apartment, and Glenn fell, striking his head on the tub. He received a concussion which affected his inner ear balance. This injury produced swelling and bleeding which upsets the delicate and sensitive equilibrium mechanism. Glenn suffered from persistent and disabling symptoms of dizziness, nausea and a ringing noise which markedly restricted his physical movements.
Weeks went by and his recovery remained slow. Doctors barred active campaigning. Supporters believed that he may have won the 5 May primary even without campaigning. However, on March 30, Glenn withdrew from the Senate race. He then went on convalescent leave from the Marine Corps in order to make a full recovery. He said he had decided to retire from the Marines when his retirement was acceptable. He could not retire until he passed his physical examination or his condition became static.
He was promoted to the rank of Colonel by the Marine Corps on October 27, 1964 and after 23 years of distinguished service to his country, Glenn retired from the Marines on January 1, 1965.
In February 1965, he was named as a consultant to the NASA administrator and remained based in Houston, Texas. For the next five years, Glenn worked primarily as an executive with Royal Crown International, a soft drink company based in Atlanta, Georgia. He also served in the boards of several other corporations and made investments in hotel developments. When the aging Senator Stephen M. Young announced his intention to retire from politics in 1970, Glenn again announced his candidacy for Young's Senate seat.
Glenn's campaign was badly organized and underfunded, and he was defeated. He learned from the defeat, however. He remained with Royal Crown until he won his seat in the U.S. Senate in November 1974 carrying all 88 counties of Ohio and was re-elected in 1980 with the largest margin in Ohio history.
In 1983, he announced his intention to gain the Democratic presidential nomination in 1984. But, his campaign, like his 1970 Senate campaign, was considered by observers to be inefficient and unfocused. He dropped out of the race prior to the convention. Ohioans returned him to Senate for a third term in 1986, again with a substantial majority. In 1992, Glenn again made history by being the first popularly elected Senator from Ohio to win four consecutive terms.
As a member of the 105th Congress, he was the Ranking Member of both the Governmental Affairs Committee and the Subcommittee on Airland Forces in the Senate Armed Services Committee. He also served on the Select Committee on Intelligence and the Special Committee on Aging. He was considered one of the Senate's leading experts on technical and scientific matters, and is still widely respected for his work to prevent the spread of weapons of mass destruction.
On February 20, 1997, the anniversary of his historic spaceflight, Senator John H. Glenn, Jr. announced his plans to retire from the Senate.
