Mark A. Plummer, "Oglesby, Richard James," American National Biography Online, February 2000, http://www.anb.org/articles/04/04-00751.html.
After Oglesby returned to Decatur he began presenting what became quite popular speeches about his travels [in Europe]. The increased name recognition made him a viable Seventh District Republican congressional candidate in the 1858 Illinois election, which featured the Lincoln-Douglas debates. Both Lincoln and Oglesby lost their 1858 election bids, but the Illinois Republicans made a comeback in 1860, when Oglesby was elected to the state senate while contributing to Lincoln's successful campaign for president. It was Oglesby who devised the "rail-splitter" sobriquet for Lincoln at the Illinois state convention at Decatur.