James Howard McGrath was born on November 28, 1903, in Woonsocket, Rhode Island. He graduated from Providence College in 1936 and received a law degree from Boston College in 1929. McGrath was governor of Rhode Island from 1940 until 1945, but he resigned in September 1945 when President Harry S. Truman appointed him U.S. solicitor general.

McGrath resigned that post in October 1946 in order to campaign for the U.S. Senate. He won his election and remained in the Senate until 1949. McGrath was also the chairman of the Democratic National Committee from 1947 until 1949. President Truman appointed him attorney general in 1949, and McGrath held that post from July of that year until April 1952. He ran unsuccessfully for both the Democratic presidential nomination in 1956 and a U.S. Senate seat from Rhode Island in 1960, working in the interim and thereafter as a lawyer in Washington, D.C. and Providence, Rhode Island. McGrath died of heart failure on September 2, 1966.