Incumbent Sen. John Hickenlooper (D) defeated Julie Gonzales (D) in the Democratic primary for the U.S. Senate in Colorado on June 30, 2026.
Ahead of the primary, Colorado Politics' Thelma Grimes wrote that "Gonzales is running on a message of generational change, arguing that Democrats need a more aggressive approach and that a vote for Hickenlooper will just mean 'more of the same.' Hickenlooper, a fixture in politics for decades, is campaigning on experience and stability, highlighting his work in the U.S. Senate and his record as Denver's mayor and Colorado governor."
Hickenlooper was elected to represent Colorado in the U.S. Senate in 2020. He previously served as governor of Colorado from 2011 to 2019 and mayor of Denver from 2003 to 2011.