John Coit Spooner of Wisconsin was widely regarded as the Senate's leading constitutional expert of his time. Chairmain of the Committee on Rules, Spooner was a member of the Senate Four, a group of powerful senators who dominated Senate action around the turn of the 20th century. Spooner was a highly skilled orator and debater, and became a close advisor to Presidents William McKinley and Theodore Roosevelt. As a member of the "old guard" faction of the Republican Party, Spooner was among those attacked in David Graham Phillips' exposé articles, "The Treason of the Senate," published in Cosmopolitan magazine in 1906.