Barnes was born in Albany, New York, and graduated from The Albany Academy in 1884 and Harvard University in 1888. He worked briefly as a newspaper reporter for the "Albany Evening Journal" before purchasing the "Albany Morning Express", of which he was publisher and editor. In 1889 he purchased the "Evening Journal", of which he was also editor and publisher. Barnes became active in New York politics as a leader of the Republican Party. In 1891, he became head of the party in both the city and in Albany County, and in 1894 Republican Oren E. Owen won the mayor's office. This victory brought about Republican dominance in Albany, and Barnes went on to serve as a member of the New York Republican State Committee from 1892 to 1914, and the committee's chairman from 1911 to 1914. He was a delegate to the Republican National Conventions of 1904, 1908, and 1912, and a member of the Republican National Committee from 1912 to 1916. As an ally of Thomas C. Platt, Barnes became a major figure in national Republican politics; his support for successive Republican presidents William McKinley, Theodore Roosevelt, and William Howard Taft led to his appointment as the U.S. Surveyor of Customs for the Port of Albany, a lucrative position he held from 1899 to 1911. In 1915, he was a delegate to the New York state constitutional convention.