Arthur Gorman was born in Woodstock, Maryland, on 11th March, 1839. After attending local schools he was appointed a page in the House of Representatives in 1852. He eventually became private secretary to Stephen Douglas. Later he served as postmaster in the Senate office.
In 1866 Gorman was appointed collector of internal revenue for the fifth district of Maryland. Later he became president of the Chesapeake Ohio Canal Company.
A member of the Democratic Party, Gorman was elected to the Senate in 1880. Over the next twenty years Gorman was chairman of various committees including the Committee on Private Land Claims and the Committee on Printing.
In 1906 David Graham Phillips wrote a series of articles published in Cosmopolitan claiming that politicians were receiving huge payments from large corporation to argue their case in the Senate. Phillips claimed that the main figures in this scandal was Gorman and Nelson W. Aldrich of Rhode Island.
Arthur Gorman died in Washington on 4th June, 1903.
Senator Nelson W. Aldrich of Rhode Island, who was singled out for special attack because of his connection with the Rockefellers and because of his tariff legislation, which, it was charged, favoured the oil and tobacco trusts. Aldrich, a Republican, was called the right arm of the interests, and Senator A. P. Gorman of Maryland, a Democrat, was called the left arm. Phillips, referring to this interest in business affairs which Democrats and Republicans alike displayed, spoke of the Senate "merger".