Also on March 2, Congress passed the Tenure of Office Act over the President's veto, in response to statements during the Swing Around the Circle that he planned to fire Cabinet secretaries who did not agree with him. This bill, requiring Senate approval for the firing of Cabinet members during the tenure of the president who appointed them and for one month afterwards, was immediately controversial, with some senators doubting that it was constitutional or that its terms applied to Johnson, whose key Cabinet officers were Lincoln holdovers.[148]

Impeachment
Main articles: Impeachment of Andrew Johnson and Impeachment trial of Andrew Johnson
"The Situation", a Harper's Weekly editorial cartoon, shows Secretary of War Stanton aiming a cannon labeled "Congress" to defeat Johnson. The rammer is "Tenure of Office Bill" and cannonballs on the floor are "Justice".
Secretary of War Edwin Stanton was an able and hard-working man, but difficult to deal with.[149] Johnson both admired and was exasperated by his War Secretary, who, in combination with General of the Army Grant, worked to undermine the president's Southern policy from within his own administration. Johnson considered firing Stanton, but respected him for his wartime service as secretary. 