He graduated from Friends School, Providence, Rhode Island in 1894, from Colby College in 1898, and from the law department of the University of Maine at Orono in 1904.

In 1930 Nelson served on a House Committee convened by Rep. Hamilton Fish III of New York to investigate communist activity in the United States.

Nelson refused to sign it, and issued his own minority report, finding that "communism is making no menacing headway in America" and recommending that no new legislation need be enacted.

[2] Nelson was defeated in the 1932 election, which, coming in the early years of the Great Depression, was a statewide landslide for Democrats.

He was further hurt by the presence in the race of an "Independent Republican", Frederick E. Bonney, whom he accused of being a 'spoiler' for his Democratic rival, Edward C. Moran.