Former Gov. John Hickenlooper (D) has defeated incumbent Sen. Cory Gardner (R) in Colorado's Senate race, AP projects.

Why it matters: It's the first Senate seat that Democrats have flipped this election as they seek to take control of the upper chamber.

The big picture: In the lead up to the election, polls consistently showed Hickenlooper with a comfortable lead against Gardner. Cook Political Report rated the race as "leans Democratic."

• Hickenlooper, who served as governor from 2011-2019, ran for the Democratic Party's presidential nomination earlier this year, but failed to gain major traction in the polls.
• Gardner was first elected in 2014 and had branded himself as a fierce ally of President Trump, including on controversial issues like the impeachment trial and Brett Kavanaugh's confirmation to the Supreme Court.