Jean Baker, "Cameron, Simon," American National Biography Online, February 2000, http://www.anb.org/articles/04/04-00195.html.
In 1856 Cameron joined the Republican party, which absorbed many Know Nothings, and that year John Frémont, the first presidential candidate of the new party, briefly favored him for vice president. In 1857 Cameron returned to the U.S. Senate after a campaign that Thaddeus Stevens likened to "wholesale private bribery." Charges of bribing voters were too vague for official action, although a brief investigation was conducted. Despite his unsavory reputation, through hard work and the use of his personal contacts Cameron emerged as an important national leader of the Republicans and one of the party's national strategists. In the Senate he opposed the English Bill, which would have admitted Kansas immediately if the territory accepted the proslavery Lecompton constitution and a reduced land grant. He was best known for his active lobbying for tariffs protecting his state's coal and iron interests.