Former Colorado House Majority Leader Alice Madden is the latest Democrat to enter the crowded primary to challenge Republican U.S. Sen. Cory Gardner.
With her entry, there are now 12 Democrats seeking to unseat Gardner.
Madden told Colorado Politics she plans to bring a focus on combating climate change to the race.
"We don't have a lot of time to act," she said. "Washington, D.C., is a chew-you-up-and-spit-you-out kind of place, and if you don't know how to get things done there, you're going to spin your wheels. We don't have that time to waste. I feel I can go there and make things happen."
Madden worked in Colorado state government and in the Obama administration on clean energy issues after serving in the state House of Representatives until 2008, including two terms as Democratic leader.
She said her experience in the Colorado House has helped prepare her to "get [stuff] done" if she's elected to the U.S. Senate.
"My nickname at the Colorado legislature was 'Geneva,'" Madden said with a laugh. "I was the person who could go in and talk to the crankiest member across the aisle, bring them to the same place. You have to approach a conversation with what they want and need. You could go [to the Senate)]and waste a couple of years trying to figure out how to build a coalition."
She acknowledged that it could be more difficult to bring around Senate GOP Leader Mitch McConnell than it was to persuade Colorado Republicans.
"I'm not naive, though, but I would try to build that professional relationship. Maybe you don't talk about climate, you talk about jobs, approach it from a purely economic standpoint."
Madden is the most prominent woman in a Democratic field where most of the other well-known candidates are men.
She said she began considering a run for the Senate after the potential candidate she'd been backing, former House Speaker Crisanta Duran, decided instead to challenge 12-term U.S. Rep. Diana DeGette in a primary.
"I wanted to support Crisanta," Madden said. "I really wanted a woman to win this race — I think it's time. Then she changed her mind, and that came as a surprise. Multiple women started calling me and asking if I would be interested."
Other Democratic contenders in the Senate race include former state Sen. Mike Johnston, former Colorado House Speaker Andrew Romanoff, former U.S. Attorney John Walsh and Dan Baer, a former diplomat in the Obama administration and the director of Colorado's Department of Higher Education under Gov. John Hickenlooper.
Stephany Rose-Spaulding, a professor and pastor, is also running after unsuccessfully challenging Republican U.S. Rep. Doug Lamborn last year, as are several other women who haven't run for office previously.
The rookie candidates include scientist and educator Trish Zornio, community organizer Lorena Garcia, climate activist Diana Bray and economist Ellen Burnes, a former chair of the Boulder County Democrats.
Pharmacist Dustin Leitzel and veterans advocate Keith Pottratz are also running.
Additional Democratic candidates have said they're considering getting in the race, including U.S. Reps. Ed Perlmutter and Joe Neguse, Secretary of State Jena Griswold and state Sens. Kerry Donovan of Vail and Angela Williams of Denver.
Madden narrowly lost a 2016 statewide race for the University of Colorado board of regents to Republican Heidi Ganahl, a result she says supports her contention she's the best choice to take on Gardner.
"I got over 1.2 million Coloradans to vote for me — way more than Cory Gardner got," she said.
Madden's 1,237,693 votes trailed Ganahl's total by just over 2% but exceeded the 983,891 votes Gardner received in the lower-turnout 2014 midterm election, when Gardner unseated Democratic U.S. Sen. Mark Udall by the same margin.
"It's obviously a comparison that's out there, but I don't think it's apples to apples. This is a completely different deal," Madden said, noting that she'd only campaigned part-time in the lower-profile regent race but was taking a leave of absence from her job at the University of Colorado Law School to run for the Senate.
Nicholas Riccardi of The Associated Press contributed