Robert B. Morgan, a North Carolina Democrat who was a freshman U.S. senator when he cast crucial votes in favor of treaties that transferred control of the Panama Canal to the Panamanian government, a decision that brought a swift end to his Senate career but which he stood by all his life, died July 16 at his home in Buies Creek, North Carolina. He was 90.

The cause was complications from Alzheimer’s disease, said his former Senate chief of staff, Carroll Leggett.

Morgan practiced law and ascended the ranks of North Carolina politics before his election to the U.S. Senate in 1974. He served in the North Carolina state Senate, including a stint as president pro tempore, from 1955 to 1969 and later was state attorney general, developing a reputation as a hard-charging activist for consumer rights.

In the U.S. Senate, he assumed the seat vacated by retiring Sen. Sam J. Ervin Jr., D, who was rocketed to national attention as chairman of the Senate committee that investigated the Watergate scandal during the Nixon administration.

Morgan accumulated a voting record that “defies ideological labels,” according to the Almanac of American Politics. He was liberal on some issues but conservative on others, and he gained his greatest prominence on the matter of the Panama Canal.

The canal and surrounding area, a critical waterway that connects the Pacific and Atlantic oceans, had been controlled by the United States since 1903, an arrangement that by the 1970s had caused increasing friction with the Panamanians.

President Jimmy Carter, elected in 1976, became persuaded that authority over the canal should reside with the Panamanian government. Opponents of his position regarded any treaty to that effect as a “giveaway.”

Morgan was initially among those opponents. He changed his position after visiting Panama as a member of the Senate Intelligence Committee and meeting with the CIA contingent there and with Panamanian leaders.

“Our relationship with Panama on the future of the canal is a festering sore and affects our relations not only with Latin America but with the rest of the world,” the News and Observer of Raleigh, North Carolina, quoted Morgan as saying in a 1977 speech. “Our global position as world leader and a moral standard bearer is seriously weakened by maintaining this vestige of colonialism.”

The treaties were signed in 1977 but faced withering opposition.