He was raised in Eastport, Maine, and Franklin, New Hampshire, and graduated from Phillips Exeter Academy in 1887.

After graduating, though he considered a job teaching Latin and Greek, he instead joined the Concord Monitor,[1] and became a newspaper editor.

In 1909 Moses was appointed by President William Howard Taft to be the United States Minister to Greece and Montenegro, and he served until 1912.

Moses won narrowly in his 1918 special election to complete the term of Jacob H. Gallinger, and he was handily reelected in 1920 and 1926.

He ran unsuccessfully for reelection in 1932, losing narrowly to the Democrat nominee and Former Governor Fred H. Brown in the Democratic landslide that also saw Franklin D. Roosevelt nationally defeat Herbert Hoover in that year's presidential election.