Democrat John Hickenlooper, Colorado’s former governor, has picked off incumbent GOP Sen. Cory Gardner, NBC News projects.
Hickenlooper’s victory is the outcome Democrats were counting on in the party’s fight to claim the Senate majority from Republicans.
With about 84 percent of the vote counted, Hickenlooper had 54.6 percent and Gardner 43.4 percent.
Hickenlooper said climate change, racial justice and Covid-19 would be among his top priorities in the Senate.
"Clearly people are saying it's time to turn the page, it's time for a different approach, it's time to start solving problems and helping people," he told supporters in a Facebook Live address. "And that's exactly what I intend to do."
In his concession speech, Gardner touted his bipartisan record and congratulated Hickenlooper.
"Please understand, to all the people who have supported our efforts tonight that his [Hickenlooper's] success is Colorado's success and our nation and our nation and state need him to succeed," Gardner said.
In the months before Election Day, polls consistently showed Hickenlooper ahead in once purple, now blue-leaning Colorado — to the point where a major Democratic group, Senate Majority PAC, canceled a $1.2 million ad buy with two-and-a-half weeks to go, counting the seat as a win.
GOP campaign groups spent only nominally in the state, virtually abandoning Gardner, one of most vulnerable Republican incumbents of this cycle.
“There is no reason for either side to put another dime into this state,” David Flaherty, a GOP pollster from Colorado, told The Denver Post in early October. "It's over."
Hickenlooper, 68, briefly ran for president, but his moderate, pro-business agenda failed to pick up any momentum. He dropped out months before the Iowa and New Hampshire primaries and later announced his Senate candidacy.
Gardner, 46, won his seat in 2014, edging incumbent Democrat Mark Udall by about 2 percentage points. Hickenlooper was elected governor in 2010 and 2014, and was term-limited from running for third term.
Colorado's embrace of legalized, recreational marijuana expanded under Hickenlooper's tenure as governor.
He initially resisted the pro-pot movement, famously calling Colorado voters "reckless" for approving Amendment 64, which in 2012 paved the way for high times in the Rocky Mountain State.
He has since come around on the issue and said federal guidelines on marijuana should be adjusted so budding cannabis entrepreneurs could partake in business opportunities.