After the war, Logan resumed his political career, now as a Republican, and was a member of the United States House of Representatives from 1867 to 1871, and of the United States Senate from 1871 until 1877 and again from 1879 until his death in 1886. His re-election bid in 1885 was contentious, and Logan only won after a Democratic representative died and was replaced with a Republican. After the war, Logan, who had always been a staunch partisan, was identified with the radical wing of the Republican Party. His forceful, passionate speaking, popular on the platform, was less effective in the halls of legislation. In 1868, he was one of the managers in the impeachment trial of U.S. President Andrew Johnson. One of Logan's issues in the Senate was his efforts to stop any action taken to overturn the conviction in the court-martial of Maj. Gen. Fitz John Porter.