In the late 1870s, a combination of hard times for farming in general and the death of his child in a sawmill accident drove Simpson to move south, to Barber County, Kansas, where he bought a ranch and a herd of cattle.

[2] In late 1883 and early 1884, a long, hard winter killed his entire herd, and Simpson was reduced to working as the town marshal in Medicine Lodge, Kansas.

Simpson's Republican opponent was Colonel James Reed Hallowell, often referred to as "Prince Hal", an attorney for a railroad who campaigned from the back of a private rail car.

Simpson, campaigning on a populist platform of public ownership of railroads, a graduated income tax, the abolition of national banks, and universal suffrage, denounced Hallowell as a pampered scion of wealth, a Prince whose feet were "encased in fine silk hosiery."

With the help of populist campaigner Mary Elizabeth Lease, Simpson won a new nickname, "Sockless Jerry," and an 8,000-vote margin of victory in the race.

In 1892, he was re-elected by a slim 2,000-vote majority, running slightly behind James Weaver, the party's presidential nominee, who had also managed to seize the Democratic ballot line in Kansas.