He served from 1893 to 1900, when he resigned in order to assume his seat as a justice of the New York Supreme Court's 1st District, to which he had been elected in 1899.

In 1911, O'Gorman was proposed as a compromise choice for U.S. senator after Democrats in the New York State Legislature were unable to agree on a nominee.

[2] In 1886, he was active in the unsuccessful mayoral campaign of United Labor Party nominee Henry George, and in 1887 he ran unsuccessfully for district court judge as a United Labor candidate, but he later returned to the regular Democratic fold.

[2] O'Gorman practiced law from an office at the corner of Fulton Street and Broadway, and he developed a reputation for effective representation in civil trials.

He was a delegate to the 1896 Democratic National Convention, and afterwards supported the unsuccessful ticket of William Jennings Bryan and Arthur Sewall in the general election.

[2] In 1892, O'Gorman was elected judge of New York City's 11th District Civil Court, and he served from 1893 to 1900.

[8] Democrats nominated William F. Sheehan, who had served as lieutenant governor from 1892 to 1894 and had the support of Tammany Hall.

[10] This faction ("The Insurgents") pledged not to support Sheehan, and was large enough to prevent him from obtaining a majority in the legislative election.

[10] Balloting took place throughout January, February, and March, with Sheehan's support shifting between 63 and 86 votes, well short of the 101 needed to win.

[10] The deadlock was finally broken when Charles Francis Murphy, the "boss" of Tammany Hall, proposed O'Gorman as a compromise.

[13] In addition, he served at different times on the committees on Foreign Relations, Immigration, Judiciary, Manufactures, Naval Affairs, and Rules.

[15] He was frequently called on by the New York Supreme Court to serve as a referee in civil cases, which included the mid-1920s dispute among the heirs of Jay Gould.