With the South still disenfranchised and Northern public opinion behind the Republicans, they gained a two-thirds majority in both houses of Congress. Garfield, having overcome his challengers at the district nominating convention, won reelection easily.[92]
Garfield opposed the proposed impeachment of Johnson initially when Congress convened in December 1866, but supported legislation to limit Johnson's powers, such as the Tenure of Office Act, which restricted Johnson's ability to remove presidential appointees.[93] Distracted by committee duties, Garfield spoke about these bills rarely, but was a loyal Republican vote against Johnson.[94]
On January 7, 1867, Garfield voted in support of the resolution that launched the first impeachment inquiry against Johnson (run by the House Committee on the Judiciary).[95] On December 7, 1867, he voted against the unsuccessful resolution to impeach Johnson that the House Committee on the Judiciary had sent the full House.[96] On January 27, 1868, he voted to pass the resolution that authorized the second impeachment inquiry against Johnson (run by the House Select Committee on Reconstruction).