A delegate to the Pennsylvania constitutional convention of 1838, he refused to sign the document because it limited voting to whites.
As a Congressman, Stevens during the Civil War urged the administration to free and arm the slaves and by 1865 favored black suffrage in the South. He became one of Andrew Johnson's fiercest critics and an early advocate of his impeachment.
To Stevens, Reconstruction offered an opportunity to create a "perfect republic" based on the principle of equal rights for all citizens. As floor leader of House Republicans, he helped to shepherd Reconstruction legislation through Congress, although he thought much of it too moderate.
His plan for confiscating the land of Confederate planters and dividing it among Northern settlers and the former slaves failed to pass.