After he was released in a prisoner exchange, he was appointed to the United States Military Academy by Abraham Lincoln.

[4] The state's Democratic leaders took notice and made Peck the party's nominee for the 1890 gubernatorial race.

Peck won the election, beating the incumbent William Hoard, and resigned as Milwaukee's mayor on November 11, 1890.

He was reelected as governor in 1892, defeating Republican John C. Spooner, but lost a third term to William Upham in 1894.

He ran again in 1904 but lost to the incumbent Robert M. La Follette Sr.[3] Peck died in 1916 in Milwaukee at age 75 of Bright's disease and was buried at Forest Home Cemetery.