Former Colorado Gov. John Hickenlooper won the state's Democratic primary for the U.S. Senate on Tuesday evening, per AP.

Why it matters: Hickenlooper will now face off against Sen. Cory Gardner — largely considered one of the most vulnerable Republicans in the November general elections. But the former governor has faced recent backlash over past comments and ethics complaints.

• Hickenlooper apologized this month for his 2014 comments comparing public officials to slaves being whipped on an "ancient slave ship."
• An ethics committee determined that Hickenlooper violated state law by accepting gifted rides in a private jet and a Maserati limousine, per the Washington Post. He was fined $3,000, and held in contempt after failing to appear for the first day of hearings on the matter.

Between the lines: Hickenlooper was the latest establishment Democrat to face a possible upset from a more progressive challenger — in this case, former state House Speaker Andrew Romanoff.

• 16-term Rep. Eliot Engel (D) was notably defeated last week in the New York primaries by Jamaal Bowman, a progressive former middle school principle.
• Amy McGrath, a 2018 sweetheart of the Democratic Party, nearly lost to progressive Charles Booker in the Kentucky Democratic Senate primary amid ongoing pressure from Black Lives Matter activists.
• In Colorado, Romanoff was in favor of Medicare-for-All and the Green New Deal — both policy positions that Hickenlooper has veered to the right of.