A blue wave swept Colorado politics in 2018. Democrats won races for governor, attorney general, secretary of state and took control of the state Legislature. But in terms of registered voters, Colorado is getting more and more purple.

Democrats – who have had about the same number of registered voters as Republicans for the past decade – now outpace their counterparts by about 50,000 active voters. Unaffiliated voters are the state’s largest voting bloc with nearly 315,000 more active voters than Democrats, according to the Colorado Secretary of State.

Paul DeBell, a political science professor at Fort Lewis College, said major political parties losing rank-and-file support is an international trend called party dealignment. Disillusionment with government and partisan politics play roles in the shift from traditional political parties, research suggests. Colorado’s 2016 measure to allow unaffiliated voters to participate in the major parties’ primary elections may also contribute to party dealignment, DeBell added.

Rep. Scott Tipton, R-Cortez, who is up for re-election in 2020, said independent thought is part of Colorado culture.

“Coloradans have always been independent-minded,” Tipton said in an email. “This self-reliant spirit is almost unique to the West and that independence is what makes Colorado such a special place.”

As unaffiliated voters increase their plurality in Colorado, Democratic and Republican candidates continue to covet their vote. Republicans, though, may face a tougher path to victory in statewide races in 2020.

A Republican presidential nominee hasn’t won in Colorado since George W. Bush in 2004. Democratic dominance in recent elections and unaffiliated voters’ tendency to lean left combine to make the Colorado U.S. Senate race one of the most competitive in the 2020 cycle.

Republican Sen. Cory Gardner, an affable politician from Yuma joined the Senate in 2015 after defeating Democratic incumbent Mark Udall by 1.9 percentage points. He rose to party leadership two years later when he was chosen to chair the National Republican Senatorial Committee, making him the Senate’s sixth ranking Republican at the time.

In an email to The Durango Herald, Gardner said getting things done is more important to Colorado voters than identifying as a Republican or a Democrat.

“I have been ranked the most effective member of the Colorado delegation and am the 5th most bipartisan senator,” Gardner said. “Whether it is moving the Bureau of Land Management to Western Colorado or fighting to protect our public lands, I will continue to fight for solutions that benefit Colorado above all else.”

As Gardner’s first term winds down, nearly a dozen candidates are competing in the Democratic primary for a chance to unseat him.

“I’d expect (it) to be a pretty tough race. It’ll really matter who’s on the top of the ticket and who the Democrats have going up against Gardner,” DeBell said. “Democrats and Republicans nationally will be watching this race really carefully and will probably be putting a lot of money into (it).”

Gardner’s campaign raised more than $2 million last quarter and earned the endorsement of Americans for Prosperity Action, the political arm of the Koch network. Charles and David Koch, who died Friday, are fossil fuel magnates and influential conservative donors.

While the field of Democratic candidates features legitimate contenders such as former state House Majority Leader Alice Madden of Boulder and former state Sen. Mike Johnson, national Democrats have successfully courted former governor John Hickenlooper, who swapped out his White House bid to make a run for Senate, he announced Thursday.

“I’ve always said Washington was a lousy place for a guy like me who wants to get things done. But this is no time to walk away from the table. I know changing Washington is hard, but I want to give it a shot,” Hickenlooper said before knocking in a pool hall trick shot in his video announcement.

Hickenlooper may enter the race as a favorite, but candidate and state Sen. Angela Williams warned that he is no shoo-in to win the Democratic nomination.

“This won’t be a coronation,” she said in a prepared statement.

As a presidential candidate, Hickenlooper ran as a centrist and distanced himself from liberal policies such as Medicare for All and the Green New Deal. Gardner has taken a similar approach in the Senate race, striking a centrist tone, perhaps to try to appeal to moderate, unaffiliated voters.

In a recent advertisement, Gardner characterized positions taken by some Democrats – such as government-sponsored health care and eliminating the electoral college – as “socialism on full display.”

DeBell said nominating a moderate candidate could persuade voters in the middle, but noted that a candidate advocating for broad structural change may energize voters more so than a moderate.

Bernie Sanders – who is calling for a “political revolution” to overhaul Washington – defeated eventual Democratic nominee for president, Hillary Clinton, by 19 percentage points in Colorado’s 2016 Democratic caucus. Unaffiliated voters couldn’t participate in major party caucuses until 2018, however.

Dealignment is also taking place on the Western Slope, where the number of unaffiliated voters in Colorado’s 3rd Congressional District has surpassed those in the major parties, respectively. Republican voters maintain a 5 percentage point edge on Democrats in the sprawling district. Rep. Scott Tipton, R-Cortez, ousted Democratic incumbent John Salazar in 2010 and has held the seat ever since.

“Tipton faces an easier path on the Western Slope,” DeBell said. “Yes, the independent share is growing, but there are a lot more Republicans supporting (him) – and independents leaning Republican – with it being so rural.”

Tipton easily beat former Democrat state Rep. Diane Mitsch Bush of Steamboat Springs in 2018 by 8 percentage points. Mitsch Bush, who is running again in 2020, will face a stiff challenge in the Democratic primary from state Rep. Donald Valdez of La Jara.

Valdez wants to lower prescription drug prices, increase health care access in rural areas and boost funding for public schools, according to a fundraising email.

“Even Scott Tipton can’t call me a socialist,” Valdez wrote.

Tipton said his district’s growing plurality of unaffiliated voters hasn’t changed how he campaigns or represents his constituents.

“I don’t look at problems through a partisan lens,” Tipton said in an email. “Every day I focus on solving problems for the constituents of the 3rd Congressional District.”

Expanding veterans’ health care, growing the economy and protecting public land and water are the non-partisan issues Tipton cited. While he does not support the Colorado Outdoor Recreation and Economy Act – the vast wilderness bill backed by Democratic members of the state’s delegation to U.S. Congress – Tipton proposed a smaller Colorado public lands package last month.

National Democrats are also making a play for Tipton’s seat. The Democratic Congressional Campaign Committee, the campaign arm of U.S. House Democrats, ran attack ads in June calling for Tipton to host more public events.

Tipton’s campaign spokesperson previously told the Herald he wasn’t concerned by the ads because they “amount to a cheap PR stunt, not an actual investment in the race.”

James Marshall is a student at American University in Washington, D.C., and an intern for The Durango Herald.