In the 1868 impeachment trial of President Andrew Johnson , Trumbull voted to acquit Johnson despite heavy pressure from other Republican senators . He was a candidate for the presidential nomination at the 1872 Liberal Republican convention but the fledgling party nominated Horace Greeley instead . Trumbull left the Senate in 1873 to establish a legal practice in Chicago . Before his death in 1896 , he became a member of the Populist Party and represented Eugene V. Debs before the Supreme Court
1872 Liberal Republican convention
1872 Liberal Republican convention
Lyman Trumbull