A new generation of grassroots progressive activists powered Colorado Democrats to historic victories at the state level in 2018. Now they plan to help the party capture a U.S. Senate seat.

“This is the force that helped win the House of Representatives last cycle,” 2020 Democratic Senate candidate Mike Johnston told a crowd of activists from Indivisible and other groups on Sunday, June 9. “This is the force that will help flip the U.S. Senate in this cycle.”

Johnston and seven other candidates in an ever-widening primary field spoke at the campaign’s first candidate forum on Sunday at Denver’s Barnum Park, making their case to more than a hundred attendees for why they should be Democrats’ choice to unseat Republican incumbent Senator Cory Gardner in 2020. It’s fitting that the primary campaign’s unofficial starting point would be hosted by local Indivisible groups, which have reinvigorated Democratic politics since being formed in the aftermath of Donald Trump’s election.

“It’s kind of like we’ve already been waging a campaign against Cory for the last two, three years,” says Dana Miller, an Indivisible Denver activist. “One of the things that’s so exciting about Indivisible is that because we have worked so hard and showed up in so many arenas, we have credibility.”

It was the grassroots organizing and energy of groups like Indivisible, a network of progressive activists with over 5,000 chapters nationwide, that helped Democrats rebound at the ballot box after the disappointment of 2016. In Colorado, the “Blue Wave” flipped Aurora’s 6th Congressional District, powered Governor Jared Polis to a landslide victory, swept Republicans out of three other statewide offices and helped Democrats capture the state Senate for the first time in four years.

Now, Democratic activists are looking ahead to 2020 — and while they’re no doubt motivated to throw Trump out of the White House, some view the contest for control of the Senate as even more important.

“We can elect whoever everybody thinks is the best president — they’re not going to pass any actual policy into law without a Senate that has leadership,” says Katie Farnan of Indivisible Front Range Resistance. “If Mitch McConnell is there, that’s not really possible. So we start here in Colorado; we start with our Senate race.”

Gardner is widely viewed as 2020’s single most vulnerable Senate Republican, facing an uphill battle to win re-election in a state that Hillary Clinton won by five points in 2016 — a margin that Polis more than doubled last year. The candidate that emerges from Democrats’ crowded primary field is likely to enter next year’s general election as a strong favorite.

Aside from Johnston, candidates at Sunday’s event included Andrew Romanoff, a former speaker of the Colorado House; former House majority leader Alice Madden; professor and pastor Stephany Rose Spaulding; former U.S. diplomat Dan Baer; and John Walsh, a former U.S. Attorney.

Party activists like the ones who gathered at Barnum Park on Sunday will play a key role in choosing a nominee. Indivisible won’t endorse a candidate during the primary, but members plan to be heavily involved as progressives build a message and a movement capable of defeating Gardner.

“What we can do is shine a light,” says Farnan. “We have a set of progressive values that are unwavering. We have the ability to be free from establishment parties and campaigns, and we will hold our elected officials accountable.”

Candidates who spoke at Sunday’s event stressed the urgent need to tackle issues like immigration, gun control, health care and more — but an early trend in the primary race is a strong emphasis on climate change, which nearly every candidate and activist identified as a top issue.

Several candidates are likely to make the need for aggressive climate policy a centerpiece of their campaigns, including Madden, who served in the U.S. Department of Energy and as a climate adviser to former Colorado Governor Bill Ritter. Diana Bray, a psychologist and climate activist from Englewood, has launched a campaign focused almost exclusively on the issue, and Trish Zornio, a biomedical researcher from Superior, has based hers on the need to correct a "lack of scientific representation in Congress."

Grassroots candidates like Bray, Zornio and Lorena Garcia, director of the Colorado Statewide Parent Coalition, add a further wrinkle to the campaign. With a crowded primary field and more than a year of campaigning left before the June 30, 2020, primary, there may be enough time — and enough energy in the Democratic base — for one or more of these long-shot candidates to overcome the disadvantages they face in running against better-funded establishment contenders.

Harry Gregory, an activist who attended Sunday's event, said his top priority is a candidate who is strong on climate change. He's looking for someone whose platform includes "at least the Green New Deal," an ambitious Congressional resolution sponsored by U.S. Representative Alexandria Ocasio-Cortez and other progressives. It would commit the federal government to a "ten-year national mobilization" to achieve 100 percent renewable energy and other climate goals.

"We're past the point where we have time for incremental steps," argues Gregory. So far, he says, Bray has been the only candidate who has impressed him.

It will be a long and busy year for Democratic Senate hopefuls, and for the activists who are committed to sending one of them to Congress in Gardner's place. But all were encouraged by Sunday's strong turnout, more than a year before any ballots will be cast.

"We're a bunch of unpaid moms and retirees putting this event together," says Miller. "Because that's how much we care about the state."