After widespread dissatisfaction with the Kansas-Nebraska Act, which allowed settlers in the new territories of Kansas and Nebraska to decide for themselves whether to allow slavery, the political forces in the North and West realigned, and in 1854 a coalition of Whigs, Free-Soilers and anti-slavery Democrats met to form a new party with the suggested name Republican.

Ezra Cornell identified himself with the new party, serving as a delegate to the first national Republican convention in February 1856. The new party met later that year, nominating John C. Frémont on a platform that included the upholding of congressional authority to control slavery in the territories and the admission of Kansas as a free state. The Democratic Party nominated James Buchanan, and the Know-Nothing Party nominated Millard Fillmore.

Cornell supported Frémont and continued to be active in the Republican Party, campaigning for Lincoln in the 1860 election.

In a letter to his wife, Cornell wrote on March 11, 1860: "Last Tuesday being the Presidents reception night ... I called up at the White house, shook hands with 'James the Usurper' [Buchanan], circulated through the gaudy apartments and gay throng untill the crowd became to dense to be pleasant when I returned to my hotel. [sic]"

Cornell was present at Lincoln's inauguration in 1861. That same year, he was elected to the New York State Legislature. Because of his experience with farm issues and his position as president of the State Agricultural Society, he was appointed chairman of the Committee on Agriculture. In the 1862 election, the Democrats made major gains in New York state, but Tompkins County remained firmly Republican. Cornell was re-elected to the Assembly, and in 1863 he was elected to the State Senate, where he served for four years, representing Broome, Tioga and Tompkins counties. In 1866, there was talk of nominating Cornell for governor of New York. (His son Alonzo B. Cornell would serve as governor from 1880 to 1883.)

Adapted by Susan S. Lang from the Web site, "Invention and Enterprise: Ezra Cornell, a Nineteenth-Century Life."