in the 1942 election, governor George A. Wilson did not run for re-election, instead he successfully ran for a seat in the United States Senate.

Hickenlooper was elected to succeed Wilson, defeating former governor Nelson Kraschel 63% to 37%, serving one term from 1943-1945.

In this position, he had an intense rivalry with Everett Dirksen, the Senate Republican leader at the time.

[8] Senator Hickenlooper was outraged by the 1967 USS Liberty incident and was one of the few Congressmen to call for an investigation.

He was openly skeptical of Israel's mistaken identity explanation: "From what I have read I can't tolerate for one minute that this was an accident.

"[9] On September 4, 1971, Hickenlooper died at the age of 75 while visiting friends in Shelter Island, New York.