Clark was an abolitionist. In the first
fugitive slave case in Ohio in 1853, George Washington McQuerry was taken into custody by men claiming he was an escaped slave. Clark was able to obtain a writ of
habeas corpus from
Judge John McLean so the case could go before the court. The case was unsuccessful and McQuerry was forced back into slavery. Clark became a member of the
Republican Party in the 1850s. He joined the
Liberal Republicans in 1872, but left after they nominated
Horace Greeley for president. He attended the
1876 Republican National Convention and supported
Rutherford B. Hayes in the
presidential election. On March 26, 1877, Clark renounced the Republicans and joined the
Workingmen's Party of the United States. He supported the
Great Railroad Strike of 1877 and gave speeches to the strikes where he condemned their repression by the state and federal government and the economic crisis. In his speeches he called for the railroads to be nationalized and that the "title of private owners should be extinguished". Later that year he unsuccessfully ran as the Workingmen's candidate for state school commissioner, becoming the first black socialist to run for office in the United States. He ran in
Ohio's 1st congressional district, garnering 275 votes, or 1.09%. The
Socialist Labor Party of America selected Clark to become a member of its National Executive Committee in 1878. Threats were made to remove him as principal of Gaines High School if he remained in the SLP, but these attempts failed due to "the colored people of Cincinnati, who had stood by me all my life-time, cam to my rescue" according to Clark. On July 21, 1879, he left the SLP as the party was not appealing to the interests of black people, but stated that he was still a socialist. In 1882, he aided county Democrats in organizing a civil rights bill, which passed into law. ==Death and legacy==